Impacts of swine manure pits on groundwater quality

A review of mitigation technologies and management strategies for greenhouse gas and air pollutant emissions in livestock production

One of the key issues in manure management of livestock production is to reduce greenhouse gas (GHG) and air pollutant emissions, which lead to significant environmental footprint and human/animal health threats. This study provides a review of potentially efficacious technologies and management strategies that reduce GHG and air pollutant emissions during the three key stages of manure management in livestock production, i.e., animal housing, manure storage and treatment, and manure application. Several effective mitigation technologies and practices for each manure management stage are identified and analyzed in detail, including feeding formulation adjustment, frequent manure removal and air scrubber during animal housing stage; solid-liquid separation, manure covers for storage, acidification, anaerobic digestion and composting during manure storage and treatment stage; land application techniques at appropriate timing during manure application stage. The results indicated several promising approaches to reduce multiple gas emissions from the entire manure management. Removing manure 2-3 times per week or every day during animal housing stage is an effective and simple way to reduce GHG and air pollutant emissions. Acidification during manure storage and treatment stage can reduce ammonia and methane emissions by 33%-93% and 67%-87%, respectively and proper acid, such as lactic acid can also reduce nitrous oxide emission by about 90%. Shallow injection of manure for field application has the best performance in reducing ammonia emission by 62%-70% but increase nitrous oxide emission. The possible trade-off brings insight to the prioritization of targeted gas emissions for the researchers, stakeholders and policymakers, and also highlights the importance of assessing the mitigation technologies across the entire manure management chain. Implementing a combination of the management strategies needs comprehensive considerations about mitigation efficiency, technical feasibility, local regulations, climate condition, scalability and cost-effectiveness.

Source identification and potential health risks of fluoride and nitrate in groundwater of a typical alluvial plain

A comprehensive understanding of the role of natural and anthropogenic factors in groundwater pollution is essential for sustainable groundwater resource management, especially in alluvial plains with intensive anthropogenic activities. Numerous studies have focused on the contribution of individual factors on groundwater pollution in alluvial aquifers, but distinguishing the effects of natural and anthropogenic factors is limited. In this study, 64 wells were sampled in different seasons from the Yellow River alluvial plain in China for hydrochemical and isotopic analysis to investigate the spatiotemporal distribution, sources and health risks of fluoride and nitrate in alluvial aquifers. Results showed that fluoride contamination was widely distributed without significant seasonal variation, and 78.1 % of the dry season samples and 65.6 % of the wet season samples showed fluoride concentrations above the permissible limit (1.5 mg/L). High-F- groundwater was generally accompanied by Na-HCO3 and Na-HCO3·SO4 water types. Fluoride was from a natural origin mainly associated with mineral dissolution, competitive adsorption, cation exchange, and evaporation. Groundwater nitrate contamination was spatially sporadic and showed significant seasonal differences. Only 13.6 % of the dry season samples and 3.2 % of the wet season samples had NO3- concentrations exceeded the permissible limit of 50 mg/L. The hydrochemical phase evolved from bicarbonate or sulfate type to chloride type with increasing nitrate concentration. Manure and sewage attributed to agricultural activities contributed the most nitrogen to groundwater, followed by soil organic nitrogen and chemical fertilizers, revealing the anthropogenic origin of nitrate. Nitrification was the dominant nitrogen transformation process in the wet season, and denitrification was prevalent in the dry season. Oral ingestion of high fluoride groundwater was a major threat to human health, especially for infants. This study provided a significant reference for water resources management in alluvial aquifers.

Determination of nitrogen sources and losses in surface runoff from different lands at a watershed scale

Nitrogen (N) loss by surface runoff inevitably results in severe N pollution and eutrophication of aquatic ecosystems. In this study, surface runoff from different land uses in the East Tiaoxi River watershed was collected, and the N concentrations, sources and losses were measured using the dual isotope (δ¹⁵N-NO₃^- and δ¹⁸O-NO₃^-), a Bayesian isotopic mixing (SIAR) model and Soil Conservation Service Curve Number (SCS-CN) method. The results showed that the N concentrations in surface runoff from agricultural lands were higher than those from urban areas and forestlands, and nitrate (NO₃^-), particulate nitrogen (PN) and dissolved organic nitrogen (DON) were the major forms of N in surface runoff in the East Tiaoxi River watershed. The total loss rate of total nitrogen (TN) from surface runoff in the East Tiaoxi River watershed was 5.38 kg·ha^-1·a^-1, with NO₃^--N (46%) contributing the most to TN loss. The TN, and NO₃^--N loss rates in surface runoff from tea planting lands (21.08 kg·ha^-1·a^-1, 11.98 kg·ha^-1·a^-1) and croplands (16.93 kg·ha^-1·a^-1, 10.96 kg·ha^-1·a^-1) were high, those from vegetable lands and urban areas were medium, and those from economic and natural forestlands were low in the East Tiaoxi River watershed. The NO₃^--N contributions of chemical fertiliser (CF), soil N (SN), sewage/manure (SM), and atmospheric deposition (AD) in surface runoff in the East Tiaoxi River watershed were 124.32 × 10³, 104.84 × 10³, 82.25 × 10³ and 58.69 × 10³ kg·a^-1, respectively. The N pollutant losses in surface runoff from agricultural lands (croplands with rice growing, vegetable lands and tea planting lands) were responsible for most of the N pollutants being transported into the East Tiaoxi River systems.

Identifying nitrogen sources in intensive livestock farming watershed with swine excreta treatment facility using dual ammonium (δ15NNH4) and nitrate (δ15NNO3) nitrogen isotope ratios axes

We proposed a novel approach based on dual ammonium and nitrate nitrogen isotope ratios (δ¹⁵N_NH4 and δ¹⁵N_NO3, respectively) axes to identify nitrogen sources in intensive livestock farming watersheds, especially those with swine excreta treatment facilities. The δ¹⁵N_NH4 and δ¹⁵N_NO3 values in water samples were measured monthly in 2016-2017. Soil and mineral fertilizers, sewage, sewage effluent, manure, and swine effluents were the five sources considered to identify nitrogen sources. The results showed that nitrogen pollution from agricultural activities was well reflected by the seasonal δ¹⁵N_NH4 and δ¹⁵N_NO3 patterns in the river, and microbial nitrification was suggested as the dominant nitrogen transformation process in the river. This study revealed that δ¹⁵N_NH4 and δ¹⁵N_NO3 axes provided better results than the traditionally used nitrate oxygen (δ¹⁸O_NO3) and δ¹⁵N_NO3 axes for identifying nitrogen sources in agricultural watersheds with swine excreta treatment facilities. The mixing model results showed that stream water was severely contaminated with swine effluents (e.g., a mean minimum contribution of 31%), thus affecting the quality of the mainstream (p = 0.068 < 0.10). This study was the first successful application of dual δ¹⁵N_NH4 and δ¹⁵N_NO3 axes to better understand nitrogen sources in intensive livestock farming watersheds with swine excreta treatment facilities.

Long-term dynamic changes in attached and planktonic microbial communities in a contaminated aquifer

Biodegradation is responsible for most contaminant removal in plumes of organic compounds and is fastest at the plume fringe where microbial cell numbers and activity are highest. As the plume migrates from the source, groundwater containing the contaminants and planktonic microbial community encounters uncontaminated substrata on which an attached community subsequently develops. While attached microbial communities are important for biodegradation, the time needed for their establishment, their relationship with the planktonic community and the processes controlling their development are not well understood. We compare the dynamics of development of attached microbial communities on sterile substrata in the field and laboratory microcosms, sampled simultaneously at intervals over two years. We show that attached microbial cell numbers increased rapidly and stabilised after similar periods of incubation (∼100 days) in both field and microcosm experiments. These timescales were similar even though variation in the contaminant source evident in the field was absent in microcosm studies, implying that this period was an emergent property of the attached microbial community. 16S rRNA gene sequencing showed that attached and planktonic communities differed markedly, with many attached organisms strongly preferring attachment. Successional processes were evident, both in community diversity indices and from community network analysis. Community development was governed by both deterministic and stochastic processes and was related to the predilection of community members for different lifestyles and the geochemical environment.

Alternative Management Systems of Beef Cattle Manure for Reducing Nitrogen Loadings: A Case-Study Approach

Livestock manure is one of the main sources of agricultural nonpoint source pollution and poses a great threat to the environment and human health. Sustainable management of manure via recycling is an effective means to tackle the problem. Based on field interviews in China, multiple case studies were employed to investigate alternative manure management systems. Four conclusions arose. First, compost-based systems, product-based systems, substrate-based systems, and biogas-based systems were identified as four main types of manure management systems, with each possessing its success factors and risk factors. The adoption of a system was driven by various factors. Second, market-oriented operation was the dominant operation mechanism of all the manure management systems. Third, compared to direct application of manure to croplands, all the four manure management systems could reduce nitrogen loadings from livestock farms and lower their environmental effects. Among the systems, biogas-based systems could reduce nitrogen loadings to the greatest extent, followed by product-based systems and substrate-based systems, and then by compost-based systems. Lastly, integrated management of manure with mixed recycling systems is imperative for reducing its environmental effects, which can benefit from the increasing role of third-party entities in manure recycling. Policy implications were also discussed.

Groundwater Quality Assessment of a Multi-Layered Aquifer in a Desert Environment: A Case Study in Wadi ad-Dawasir, Saudi Arabia

Sustainable management of groundwater in desert environments dictates better knowledge of the quality status and the controlling processes. To this end, an integrated analysis of hydrochemical and statistical assessment was carried out for 692 groundwater samples collected from the multi-layered aquifer system in Wadi ad-Dawasir area (Saudi Arabia). The four water-bearing formations arranged upwards, namely Lower Wajid, Upper Wajid, Khuff-Kumdah, and Quaternary, were investigated. The prime objective was to delineate the baseline conditions and the dominant process controlling the groundwater evolution that can help make resource management better. We used fifteen indicators, namely the total dissolved solid (TDS), total hardness, Eh, pH, temperature °C, turbidity, Fe2+, dissolved oxygen (DO), NH4, HCO3−, NO3−, F, NO2−, PO42−, and SiO2. Descriptive statistics, violation of the international standards, geostatistical modeling, and factorial analyses (FA) were performed. Geologic, soil, topographic, and climatic factors controlling the quality were investigated. The Quaternary aquifer was the most polluted by TDS, total hardness, NO3−, SiO2, Fe2+, F, and HCO3−. Khuff-Kumdah showed largest means of DO and NH4. Upper Wajid was the largest in NO2−. Lower Wajid proved largest in PO42−. Violation of the international standards clarified largest emergence of the pH for the Lower Wajid; Fe2+ and NO3− for the Upper Wajid; and total hardness, TDS, Fluoride, turbidity, and NH4 for the Quaternary aquifer. Rock interaction and evaporation are the dominant processes that contributed largely to the hydrochemical evolution of the groundwater. FA distinguished six main factors that explained for over 60.8% of the total groundwater quality variation lead byF1 (44.23%) that clarified strong positive loads of TDS (0.98), total hardness (0.95), nitrate NO3− (0.84), turbidity (0.78), NH4 (0.67), moderately loaded by fluoride (0.47), and Fe2+ (0.31).

Synergistic Tannic Acid-Fluoride Inhibition of Ammonia Emissions and Simultaneous Reduction of Methane and Odor Emissions from Livestock Waste

Gaseous emissions from livestock production are complex mixtures including ammonia, methane, volatile organic compounds (VOC), and H₂S. These contribute to eutrophication, reduced air quality, global warming, and odor nuisance. It is imperative that these gases are mitigated in an environmentally sustainable manner. We present the discovery of a microbial inhibitor combo consisting of tannic acid and sodium fluoride (TA-NaF), which exhibits clear synergistic inhibition of ammonia production in pure bacteria culture and in pig manure while simultaneously inhibiting methane and odorant (H₂S and VOC) emissions. In laboratory headspace experiments on pig manure, we used proton-transfer-reaction mass spectrometry and cavity ring-down spectroscopy to measure the effect of TA-NaF on gaseous emissions. Ammonia emission was reduced by more than 95%, methane by up to ∼99%, and odor activity value by more than 50%. Microbial community analysis and gas emission data suggest that TA-NaF acts as an efficient generic microbial inhibitor, and we hypothesize that the synergistic inhibitory effect on ammonia production is related to tannic acid causing cell membrane leakage allowing fluoride ions easy access to urease.

Quantitative identification of nitrate sources in the surface runoff of three dominant forest types in subtropical China based on Bayesian model

Nitrate pollution is a global environmental issue. Forests play an important role in altering hydrological processes and purifying water pollutants in rainfall and runoff. The quantitative identification of nitrate concentration and sources in surface runoff is of great significance for watershed management and water environment improvement. In this study, water quality of surface runoff was monitored in three typical forest types in subtropical eastern China: Phyllostachys pubescens, Cunninghamia lanceolate, and Cyclobalanopsis glauca. Combined with hydrochemical analysis, we adopted the dual isotope approach (δ¹⁵N-NO₃^- and δ¹⁸O-NO₃^-) and Bayesian model (SIAR) to identify nitrate sources in forests that are subject to low anthropogenic disturbance. Results showed that the temporal variability of NO₃-N concentrations was similar for all forest types, with higher values in periods of low rainfall and lower values in heavy rainfall periods. The NO₃^--N concentration in runoff was much higher in C. glauca forests relative to P. pubescens and C. lanceolata. Both the Cl^- concentrations and NO₃^-/Cl^- molar ratio suggested the fertilizer inputs was the dominant source of nitrate in surface runoff. In agreement, δ¹⁵N-NO₃^- and δ¹⁸O-NO₃^- values inferred atmospheric deposition and chemical fertilizers to be the main sources of nitrate in all forest types. The Bayesian model outputs demonstrated that atmospheric deposition was the main source in the runoff in P. pubescens and C. lanceolate forests, contributing 28.83% and 35.08% to the total nitrate, respectively. In contrast, chemical fertilizers were identified as the main source in C. glauca forests, with NH₄⁺ fertilizers and NO₃^- fertilizers accounting for 27.07% and 24.83%, respectively. Both chemical and isotopic analysis indicated that nitrification had little contribution to nitrate concentrations in runoff. Our results suggest that, even in forests with low anthropogenic disturbance, the application of fertilizer in surrounding agricultural regions should be effectively managed to minimize watershed nitrogen contamination.

Effect of sulfonamide pollution on the growth of manure management candidate Hermetia illucens

Antibiotics are commonly used in livestock and poultry farming. Residual antibiotics in manure may lead to antibiotic pollution of soil, surface water, and groundwater through land application and run-off rainfall. The black soldier fly (BSF) Hermetia illucens is a good candidate for manure management. We evaluated the effect of sulfonamide pollution on the growth of H. illucens. Four treatments were considered with a sulfonamide content in the feed of 0 (control group), 0.1, 1, and 10 mg/kg. The control larvae were fed without sulfonamide. Survival and development status of the individuals were recorded daily. The weights of the fifth instar larvae, prepupae, and pupae were checked. Antioxidant enzyme activity was determined with the fifth instar larvae. The results showed that a low (0.1 and 1 mg/kg) concentration of sulfonamides had no effects on larval survival, pupation, and eclosion of BSFs. A high sulfonamide concentration of 10 mg/kg had a significant effect on the survival of larvae and pupae and on the body weight of larvae, prepupae and pupae. Peak of the cumulated pupation rate and eclosion rate in the sulfonamide treatment of 10 mg/kg was very low. Pupation and eclosion in this group peaked later than that of the control and low sulfonamide concentration treatment groups (0.1 mg/kg and 1 mg/kg). Larvae from the sulfonamides group showed lower antioxidase activities than that of the control. In sulfonamide groups, the activity of peroxidase and superoxide dismutase was reduced in a concentration-dependent manner. Sulfamonomethoxine, sulfamethoxazole, and sulfamethazine were not detected in the harvested prepupae. Only sulfadiazine was discovered in the sulfonamide treatments of 1 and 10 mg/kg. In conclusion, BSFs can tolerate certain concentrations of sulfonamide contamination.

Influence of biochar on physico-chemical and microbial community during swine manure composting process

Excessive nutrients and toxic gas emissions from animal manure management are of great global concern, with negative environmental and economic consequences worldwide. Due to biochar recalcitrance and sorption properties, this study investigated the effect of the biochar(BC) derived from bamboo, amendment on swine manure(SM) composting efficiency through physical, physio-chemical, gaseous emissions, microbiological, and phytotoxic analysis during the 56 day process of in-vessel composting. The treatments were set-up from different ratios of biochar to swine manure mixed with sawdust(SD)(i.e. SM + SD + 3%BC(T1), SM:SD + 5 %BC(T2) and SM:SD + 10 %BC (T3)), while treatment without biochar amendment was used as a control, SM:SD(C). The results showed that, compared to the control, biochar amended compost mixtures had significantly reduced (p ≤ 0.05) bulk density, organic matter(OM), C:N ratio, NH₃ emission, pathogenic microorganisms, and phytotoxicity effect (Cress seed, Lepidium sativum Linn.). On the other hand, biochar amendment mixtures had increased total porosity, water holding capacity, rapid thermophilic temperature, and nitrate nitrogen. However, with the most prominent effects in terms of the nutrient quality and degradation rate of compost mixtures, the amendment of 10% biochar is recommended for swine manure management through the composting process.

A nitrogen transformation model for multi-layer enhanced groundwater remediation technology

The multi-layer enhanced groundwater remediation technology (MET) is an innovative platform that integrates physical chemistry, bioremediation, and phytoremediation technology to safely and effectively remediate ammonia nitrogen in groundwater. A nitrogen transformation model was established to study the mechanism of nitrogen transformation within ammonia nitrogen removal in the MET. The model considered organic nitrogen, ammonia nitrogen, and nitrate nitrogen as the variables, and ammonification, nitrification, denitrification, microbial assimilation, plant absorption, adsorption-desorption, and volatilization as the influencing factors. The unknown parameters of the model were obtained by fitting the data from a bench-scale experiment, and the results of the model validation and comparison showed that under the experimental initial conditions (the hydraulic load of the influent is 14.68 m³/(m² d) and the concentration of the ammonia nitrogen is 25.0 mg/L) and after the device ran for 45d continuously, the simulated and measured average concentration values of ammonia nitrogen in the effluent were 1.701 mg/L and 1.775 m/L, respectively, and the relative deviation was 4.17%. The simulated and measured average concentration values of nitrate nitrogen in effluent were 11.474 mg/L and 11.244 m/L, respectively, and the relative deviation was 2.05%, and the total removal rate was 92.07%. Thus it can be seen that the predicted values of the nitrogen transformation model were in good agreement with the measured values, and the model could be applied to forecast the long-term remediation effects of nitrogen in groundwater by MET.

Tracking nitrate sources in the Chaohu Lake, China, using the nitrogen and oxygen isotopic approach

The Chaohu Lake is highly polluted and suffers from severe eutrophication. Nitrate is a key form of nitrogen that can cause water quality degradation. In this study, hydrochemical and dual isotopic approaches were utilized to identify the seasonal variation of nitrate sources in the Chaohu Lake and its inflowing rivers. The average nitrate concentrations ([NO₃^-]) of the lake and its inflowing rivers were 89.9 and 140.8 μmol L^-1, respectively. The isotopic values of δ¹⁵N-NO₃^- and δ¹⁸O-NO₃^- in the lake ranged from - 1.01 to + 16.67‰ and from - 4.39 to + 22.20‰, respectively. The two major rivers had distinct isotopic compositions, with average δ¹⁵N-NO₃^- values of + 17.52 and + 3.51‰, and average δ¹⁸O-NO₃^- values of + 2.71 and + 7.47‰ for the Nanfei River and Hangbu River, respectively. The results show that soil organic ammonium and urban wastewater discharge were the main sources of nitrate in the Chaohu Lake, and nitrate assimilation was an important process affected [NO₃^-] and isotopic compositions, especially in the western Chaohu Lake. The elevated [NO₃^-] and δ¹⁵N-NO₃^- values in the western Chaohu Lake indicate the high influence of human activities. Urban wastewater discharge was the primary nitrate source in the Nanfei River and soil organic ammonium was the main source in the Hangbu River. Although nitrate from direct atmospheric deposition was low, its strong flushing effect can substantially improve riverine [NO₃^-] and nitrate loading from terrestrial ecosystem. The relatively high nitrate fluxes from the Hangbu River indicate that nitrogen loading from agricultural watershed is unneglectable in watershed nitrogen sources reduction strategies.

The Likelihood of Coliform Bacteria in NJ Domestic Wells Based on Precipitation and Other Factors

The influence of precipitation on coliform bacteria detection rates in domestic wells was investigated using data collected through the New Jersey Private Well Testing Act. Measured precipitation data from the National Weather Service (NWS) monitoring stations was compared to estimated data from the Multisensor Precipitation Estimate (MPE) in order to determine which source of data to include in the analyses. A strong concordance existed between these two precipitations datasets; therefore, MPE data was utilized as it is geographically more specific to individual wells. Statewide, 10 days of cumulative precipitation prior to testing was found to be an optimal period influencing the likelihood of coliform detections in wells. A logistic regression model was developed to predict the likelihood of coliform occurrence in wells from 10 days of cumulative precipitation data and other predictive variables including geology, season, coliform bacteria analysis method, pH, and nitrate concentration. Total coliform (TC) and fecal coliform or Escherichia coli (FC/EC) were detected more frequently when the preceding 10 days of cumulative precipitation exceeded 34.5 and 54 mm, respectively. Furthermore, the likelihood of coliform detection was highest in wells located in the bedrock region, during summer and autumn, analyzed with the enzyme substrate method, with pH between 5 and 6.99, and (for FC/EC but not TC) nitrate greater than 10 mg/L. Thus, the likelihood of coliform presence in domestic wells can be predicted from readily available environmental factors including timing and magnitude of precipitation, offering outreach opportunities and potential changes to coliform testing recommendations.

Groundwater Contamination Due to Activities of an Intensive Hog Farming Operation Located on a Geologic Fault in East Mediterranean: A Study on COD, BOD₅ and Microbial Load

The application of treated animal wastewater produced in intensive fog farming operations (IHFOs) on surface soil, leads to groundwater contamination. In this study, the contamination of a Mediterranean aquifer caused by long-term application of treated wastewater, produced by an IHFO, on a plot with a geologic fault within the IHFO boundaries, was investigated. Groundwater samples were taken from monitoring wells close to the IHFO. A significant increase of chemical oxygen demand (COD), biochemical oxygen demand (BOD5), total viable count (TVC) and total coliform (TC) concentrations was found in wells, compared to control monitoring well, which were mainly affected by the subsurface flow of contaminated water, due to the presence of the geologic fault. During the winter, significant increases in concentrations of COD, BOD5, TVC and TC were noted and attributed to increased precipitation, which assisted in the accelerated transport of organic compounds and microbial load, through geologic fault, to groundwater.

Spatiotemporal patterns of livestock manure nutrient production in the conterminous United States from 1930 to 2012

Manure nitrogen (N) and phosphorus (P) from livestock husbandry are important components of terrestrial biogeochemical cycling. Assessment of the impacts of livestock manure on terrestrial biogeochemistry requires a compilation and analysis of spatial and temporal patterns of manure nutrients. In this study, we reconstructed county-level manure nutrient data of the conterminous United States (U.S.) in 4- to 5-year increments from 1930 to 2012. Manure N and P were 5.8 9 ± 0.64 Tg N yr.(-1) (Mean ± Standard Deviation) and 1.73 ± 0.29 Tg Pyr.(-1) (1 Tg = 10(12)g), and increased by 46% and 92% from 1930 to 2012, respectively. Prior to 1970, manure provided more N to the U.S. lands than chemical fertilizer use. Since 1970, however, increasing chemical N fertilizer use has exceeded manure N production. Manure was the primary P source in the U.S. during 1930-1969 and 1987-2012, but was lower than P fertilizer use in 1974, 1978, and 1982. High-nutrient-production regions shifted towards eastern and western areas of the U.S. Decreasing small farms and increasing Concentrated Animal Feeding Operations (CAFOs) induced concentrated spatial patterns in manure nutrient loads. Counties with cattle or poultry as the primary manure nutrient contributors expanded significantly from 1930 to 2012, whereas regions with sheep and hog as the primary contributors decreased. We identified regions facing environmental threats associated with livestock farming. Effective management of manure should consider the impacts of CAFOs in manure production, and changes in livestock population structure. The long-term county-level manure nutrient dataset provides improved spatial and temporal information on manure nutrients in the U.S. This dataset is expected to help advance research on nutrient cycling, ammonia volatilization, greenhouse gas (GHG) emissions from livestock husbandry, recovery and reuse of manure nutrients, and impacts of livestock feeding on human health in the context of global change.

The Ecological Dynamics of Fecal Contamination and Salmonella Typhi and Salmonella Paratyphi A in Municipal Kathmandu Drinking Water

One of the UN sustainable development goals is to achieve universal access to safe and affordable drinking water by 2030. It is locations like Kathmandu, Nepal, a densely populated city in South Asia with endemic typhoid fever, where this goal is most pertinent. Aiming to understand the public health implications of water quality in Kathmandu we subjected weekly water samples from 10 sources for one year to a range of chemical and bacteriological analyses. We additionally aimed to detect the etiological agents of typhoid fever and longitudinally assess microbial diversity by 16S rRNA gene surveying. We found that the majority of water sources exhibited chemical and bacterial contamination exceeding WHO guidelines. Further analysis of the chemical and bacterial data indicated site-specific pollution, symptomatic of highly localized fecal contamination. Rainfall was found to be a key driver of this fecal contamination, correlating with nitrates and evidence of S. Typhi and S. Paratyphi A, for which DNA was detectable in 333 (77%) and 303 (70%) of 432 water samples, respectively. 16S rRNA gene surveying outlined a spectrum of fecal bacteria in the contaminated water, forming complex communities again displaying location-specific temporal signatures. Our data signify that the municipal water in Kathmandu is a predominant vehicle for the transmission of S. Typhi and S. Paratyphi A. This study represents the first extensive spatiotemporal investigation of water pollution in an endemic typhoid fever setting and implicates highly localized human waste as the major contributor to poor water quality in the Kathmandu Valley.

Aiming to understand the ecology of municipal drinking water and measure the potential exposure to pathogens that cause typhoid fever (Salmonella Typhi and Salmonella Paratyphi A) in Kathmandu, Nepal, we collected water samples from 10 water sources weekly for one year and subjected them to comprehensive chemical, bacteriological and molecular analyses. We found that Kathmandu drinking water exhibits longitudinal fecal contamination in excess of WHO guidelines. The chemical composition of water indicated site-specific pollution profiles, which were likely driven by localized contamination with human fecal material. We additionally found that Salmonella Typhi and Salmonella Paratyphi A could be detected throughout the year in every water sampling location, but specifically peaked after the monsoons. A microbiota analysis (a method for studying bacterial diversity in biological samples) revealed the water to be contaminated by complex populations of fecal bacteria, which again exhibited a unique profile by both location and time. This study shows that Salmonella Typhi and Salmonella Paratyphi A can be longitudinally detected in drinking water in Kathmandu and represents the first major investigation of the spatiotemporal dynamics of drinking water pollution in an endemic typhoid setting.

Microbial population dynamics in response to increasing loadings of pre-hydrolyzed pig manure in an expanded granular sludge bed

In recent years, pig manure (PM) has been regarded as a valuable substrate for energy and resource recovery via bioprocesses such as anaerobic digestion (AD), however, the efficiency of digesting raw PM is limited by the presence of refractory compounds. In this study, we applied a series of pretreatment on raw PM, consisting of subsequent thermochemical pretreatment, enzymatic hydrolysis, tyndallization and filtration. The liquid PM hydrolysates were fed to an expanded granular sludge bed (EGSB) for the production of biogas. The general performance and population dynamics of the EGSB reactor were assessed during an extended operational period of 339 days. An efficient and stable digestion process was achieved under high organic loading rates (OLRs) up to 21 kg-COD/(m(3)·d), agreeing with a sludge loading rate of 0.75 kg-COD/(kg-VSS·d), 1600 mg-NH4(+)-N/L and 17 mg/L of free ammonia nitrogen. The tyndallization decreased the total amount of active cells from 1 × 10(8) to 1 × 10(2) CFU/ml. Hence, bio-augmentation with pigs' intestinal microbiota was absent and the community dynamics were mainly credited to the composition of the substrate (i.e. PM hydrolysates) and the environmental conditions inside the reactor. The results showed the influence of both the seed community and the imposed loading rates on the evolutionary trajectory of the EGSB microbial community. Four bacterial genera (Clostridium, Cytophaga, Bacillus and Bacteroides) and two methanogenic genera (Methanosaeta and Methanobacterium) dominated the communities. An obvious shift from aceticlastic Methanosaeta to hydrogenotrophic Methanobacterium appeared when the OLR was increased to over 10 kg-COD/(m(3)·d).

Assessment of Bacterial Community Assembly Patterns and Processes in Pig Manure Slurry

The bacterial community assembly patterns and processes are poorly understood in pig manure slurry. We collected pig manure slurry samples during the winter and summer seasons from eight commercial pig farms in South Korea. The V3 region of 16S rRNA genes was PCR amplified and sequenced using paired-end Illumina technology for in-depth characterization of bacterial community. Firmicutes, Bacteroidetes, Proteobacteria, Spirochaetes, and Tenericutes were the predominant bacterial phyla present in slurry samples. Bacterial taxonomic community composition was not influenced by the season; however, phylogenetic community composition was affected by seasonal variations. The community composition and diversity patterns were strongly influenced by pH. The bacterial diversity indices showed a unimodal relationship with pH. Phylogenetic signals were detected over only short phylogenetic distances, revealing that closely related bacterial operational taxonomic units (OTUs) tend to co-occur in the same environment; hence, they are ecologically similar. Across all samples, a niche-based process, through strong environmental filtering imposed by pH, primarily governed bacterial community assembly; however, in samples close to the neutral pH range, the role of environmental filtering was decreased due to neutral community assembly. In summary, pH emerged as the major physico-chemical variable in pig manure slurry that regulates the relative importance of niche-based and neutral processes in shaping the community assembly of bacteria.

Source tracking swine fecal waste in surface water proximal to swine concentrated animal feeding operations

Swine farming has gone through many changes in the last few decades, resulting in operations with a high animal density known as confined animal feeding operations (CAFOs). These operations produce a large quantity of fecal waste whose environmental impacts are not well understood. The purpose of this study was to investigate microbial water quality in surface waters proximal to swine CAFOs including microbial source tracking of fecal microbes specific to swine. For one year, surface water samples at up- and downstream sites proximal to swine CAFO lagoon waste land application sites were tested for fecal indicator bacteria (fecal coliforms, Escherichia coli and Enterococcus) and candidate swine-specific microbial source-tracking (MST) markers (Bacteroidales Pig-1-Bac, Pig-2-Bac, and Pig-Bac-2, and methanogen P23-2). Testing of 187 samples showed high fecal indicator bacteria concentrations at both up- and downstream sites. Overall, 40%, 23%, and 61% of samples exceeded state and federal recreational water quality guidelines for fecal coliforms, E. coli, and Enterococcus, respectively. Pig-1-Bac and Pig-2-Bac showed the highest specificity to swine fecal wastes and were 2.47 (95% confidence interval [CI]=1.03, 5.94) and 2.30 times (95% CI=0.90, 5.88) as prevalent proximal down- than proximal upstream of swine CAFOs, respectively. Pig-1-Bac and Pig-2-Bac were also 2.87 (95% CI=1.21, 6.80) and 3.36 (95% CI=1.34, 8.41) times as prevalent when 48 hour antecedent rainfall was greater than versus less than the mean, respectively. Results suggest diffuse and overall poor sanitary quality of surface waters where swine CAFO density is high. Pig-1-Bac and Pig-2-Bac are useful for tracking off-site conveyance of swine fecal wastes into surface waters proximal to and downstream of swine CAFOs and during rain events.

Effects of an intensive hog farming operation on groundwater in east Mediterranean (I): a study on electrical conductivity, as well as nitrogen and sulfur nutrients

The discharge of treated animal wastewater produced in concentrated animal feeding operations (CAFOs) on surface soil (within CAFOs borders) leads to groundwater degradation. In this research, groundwater degradation effects of an intensive hog farming operation, located in a Mediterranean area, were investigated. Treated animal wastewater was discharged on a small plot (~10.8 ha) with a geologic fault. Groundwater samples were taken from seven groundwater monitoring wells close to the farm. These wells were affected by the subsurface flow of waters, due to the presence of the geologic fault. In the summer, a significant increase of electrical conductivity values was noted in and attributed to falling water table levels. During the winter, significant increases in concentrations of ammonium nitrogen, nitrate nitrogen, and sulfate were noted and attributed to high precipitation, which assisted in the leaching of nitrogen and sulfur to groundwater.

Effects of an intensive hog farming operation on groundwater in east Mediterranean (II): a study on K⁺, Na⁺, Cl ⁻, PO₄³⁻-P, Ca²⁺, Mg²⁺, Fe³⁺/Fe²⁺, Mn²⁺, Cu²⁺, Zn²⁺ and Ni²⁺

The application of treated animal wastewater generated in concentrated animal feeding operations on surface soil (within farm borders) leads to degradation of groundwater. Effects of an intensive hog farming operation, located at a Mediterranean limestone soil coastal area, on groundwater were investigated. Treated animal wastewater was discharged on a small plot (~10.8 ha) with a geologic fault. Samples were taken from seven groundwater monitoring wells close to the farm. A significant increase of K(+), Na(+), Cl(-), PO4 (3-)-P, Ca(2+) and Mg(2+) concentrations was found in monitoring wells which are affected by the subsurface flow of groundwater. Concentrations of Fe(3+)/Fe(2+), Mn(2+), Cu(2+), Zn(2+) and Ni(2+) in all groundwater monitoring wells were extremely low. During the winter, significant increases in concentrations of K(+) and PO4 (3-)-P were noted and attributed to high precipitation, which assisted in the leaching of K and P to groundwater.

Detection of Integrase Gene in E. coli Isolated from Pigs at Different Stages of Production System

Integrons are one of the genetic elements involved in the acquisition of antibiotic resistance. The aim of the present research is to investigate the presence of integrons in commensal Escherichia coli (E. coli) strains, isolated from pigs at different stages of production system and from the environment in an Argentinian farm. Five sows postpartum and five randomly chosen piglets from each litter were sampled by rectal swabs. They were sampled again at day 21 and at day 70. Environmental samples from the farm were also obtained. E. coli containing any integron class or combination of both integrons was detected by polymerase chain reaction in 100% of sows and in piglets at different stages of production: farrowing pen stage 68.1%;, weaning 60%, and growing/finishing 85.8%, showing an increase along the production system. From environmental samples 78.4% of E. coli containing any integron class was detected. We conclude that animals and farm environment can act as reservoirs for potential spread of resistant bacteria by means of mobile genetic elements as integrons, which has a major impact on production of food animals and that can reach man through the food chain, constituting a problem for public health.

Input and leaching potential of copper, zinc, and selenium in agricultural soil from swine slurry

Trace elements, such as copper, zinc, and selenium, used as feed additives were determined in samples of both fresh (N = 14) and anaerobically digested (N = 6) swine slurry collected on medium- to large-size farms in northeast Spain. Considering both fresh and anaerobically digested samples, mean concentrations of zinc (1,500 mg kg(-1) dry mass [dm]) were greater than those of copper (mean 239 mg kg(-1 )dm), and the selenium concentrations detected were even lower (mean 139 μg kg(-1) dm). Zinc concentrations were significantly greater in anaerobically digested samples, whereas no significant differences were found for copper or selenium. In addition, the leaching potential of zinc, copper, and selenium in cropped (lettuce heart) and uncropped experimental units subject to drip irrigation was assessed in a greenhouse experiment. Generally, the addition of swine slurry to soil (1.7 g kg(-1) dm) significantly increased zinc, copper, and selenium concentrations in leachates, which decreased in accordance with the volume of leachate eluted. Under the experimental conditions, the leaching potential of zinc and selenium was more strongly correlated with bulk parameters directly associated with the composition of the pig slurry (dissolved organic carbon, electrical conductivity, and ammonium), whereas copper mobility was more strongly associated with the crop root exudates. Although selenium has been shown to be mobile in soil, the selenium content found in the leachates did not pose any appreciable risk according to current drinking water standards.

Monitoring of nitrates in drinking water from agricultural and residential areas of Podravina and Prigorje (Croatia)

Nitrates are the most common chemical pollutant of groundwater in agricultural and suburban areas. Croatia must comply with the Nitrate Directive (91/676/EEC) whose aim is to reduce water pollution by nitrates originating from agriculture and to prevent further pollution. Podravina and Prigorje are the areas with a relatively high degree of agricultural activity. Therefore, the aim of this study was, by monitoring nitrates, to determine the distribution of nitrates in two different areas, Podravina and Prigorje (Croatia), to determine sources of contamination as well as annual and seasonal trends. The nitrate concentrations were measured in 30 wells (N = 382 samples) in Prigorje and in 19 wells (N = 174 samples) in Podravina from 2002 to 2007. In Podravina, the nitrate content was 24.9 mg/l and 6% of the samples were above the maximum available value (MAV), and in Prigorje the content was 53.9 mg/l and 38% of the samples above MAV. The wells were classified as correct, occasionally incorrect and incorrect. In the group of occasionally incorrect and incorrect wells, the point sources were within 10 m of the well. There is no statistically significant difference over the years or seasons within the year, but the interaction between locations and years was significant. Nitrate concentrations' trend was not significant during the monitoring. These results are a prerequisite for the adjustment of Croatian standards to those of the EU and will contribute to the implementation of the Nitrate Directive and the Directives on Environmental Protection in Croatia and the EU.

Nitrate source apportionment in a subtropical watershed using Bayesian model

Nitrate (NO3-) pollution in aquatic system is a worldwide problem. The temporal distribution pattern and sources of nitrate are of great concern for water quality. The nitrogen (N) cycling processes in a subtropical watershed located in Changxing County, Zhejiang Province, China were greatly influenced by the temporal variations of precipitation and temperature during the study period (September 2011 to July 2012). The highest NO3- concentration in water was in May (wet season, mean±SD=17.45±9.50 mg L(-1)) and the lowest concentration occurred in December (dry season, mean±SD=10.54±6.28 mg L(-1)). Nevertheless, no water sample in the study area exceeds the WHO drinking water limit of 50 mg L(-1) NO3-. Four sources of NO3(-) (atmospheric deposition, AD; soil N, SN; synthetic fertilizer, SF; manure & sewage, M&S) were identified using both hydrochemical characteristics [Cl-, NO3-, HCO3-, SO42-, Ca2+, K+, Mg2+, Na+, dissolved oxygen (DO)] and dual isotope approach (δ15N-NO3- and δ(18)O-NO3-). Both chemical and isotopic characteristics indicated that denitrification was not the main N cycling process in the study area. Using a Bayesian model (stable isotope analysis in R, SIAR), the contribution of each source was apportioned. Source apportionment results showed that source contributions differed significantly between the dry and wet season, AD and M&S contributed more in December than in May. In contrast, SN and SF contributed more NO3- to water in May than that in December. M&S and SF were the major contributors in December and May, respectively. Moreover, the shortcomings and uncertainties of SIAR were discussed to provide implications for future works. With the assessment of temporal variation and sources of NO3-, better agricultural management practices and sewage disposal programs can be implemented to sustain water quality in subtropical watersheds.

Diurnal pattern in nitrous oxide emissions from a sewage-enriched river

Estimates of N2O emission based on limit measurements could be highly inaccurate because of considerable diurnal variations in N2O flux due to rapid transformation of nutrients and diel change of dissolved oxygen (DO). In the present study, the N2O fluxes, dissolved N2O concentrations, and the controlling variables were measured hourly for 3d and night cycles at five sites on a typically sewage-enriched river in the Taihu region. There were no significant diurnal patterns in N2O emissions and dissolved N2O saturation, with respective mean value of 56.1μg N2O-Nm(-2)h(-1) (range=41.1μg N2O-Nm(-2)h(-1) to 87.7μg N2O-Nm(-2)h(-1)) and 813% (range=597-1372%), though distinct diurnal patterns were observed in DO concentration and river chemistry. However, the mean N2O emissions and the mean dissolved N2O saturation during the day (61.7μgNm(-2)h(-1) for N2O fluxes and 0.52μgNL(-1) for dissolved N2O saturation) were significantly higher than those during the night (50.1μgNm(-2)h(-1)for N2O fluxes and 0.44μgNL(-1) for dissolved N2O saturation). Factors controlling the N2O flux were pH, DO, NH4(+),SO4(2-), air temperature, and water temperature. Sampling at 19:00h could well represent the daily average N2O flux at the studied river.

Monitoring the perturbation of soil and groundwater microbial communities due to pig production activities

This study aimed to determine if biotic contaminants originating from pig production farms are disseminated into soil and groundwater microbial communities. A spatial and temporal sampling of soil and groundwater in proximity to pig production farms was conducted, and quantitative PCR (Q-PCR) was utilized to determine the abundances of tetracycline resistance genes (i.e., tetQ and tetZ) and integrase genes (i.e., intI1 and intI2). We observed that the abundances of tetZ, tetQ, intI1, and intI2 in the soils increased at least 6-fold after manure application, and their abundances remained elevated above the background for up to 16 months. Q-PCR further determined total abundances of up to 5.88 × 10(9) copies/ng DNA for tetZ, tetQ, intI1, and intI2 in some of the groundwater wells that were situated next to the manure lagoon and in the facility well used to supply water for one of the farms. We further utilized 16S rRNA-based pyrosequencing to assess the microbial communities, and our comparative analyses suggest that most of the soil samples collected before and after manure application did not change significantly, sharing a high Bray-Curtis similarity of 78.5%. In contrast, an increase in Bacteroidetes and sulfur-oxidizing bacterial populations was observed in the groundwaters collected from lagoon-associated groundwater wells. Genera associated with opportunistic human and animal pathogens, such as Acinetobacter, Arcobacter, Yersinia, and Coxiella, were detected in some of the manure-treated soils and affected groundwater wells. Feces-associated bacteria such as Streptococcus, Erysipelothrix, and Bacteroides were detected in the manure, soil, and groundwater ecosystems, suggesting a perturbation of the soil and groundwater environments by invader species from pig production activities.

Calibration and validation of an integrated nitrate transport model within a well capture zone

Groundwater contamination by nitrate was investigated in an agricultural area in southern Quebec, Canada, where a municipal well is the local source of drinking water. A network of 38 piezometers was installed within the capture zone of the municipal well to monitor water table levels and nitrate concentrations in the aquifer. Nitrate concentrations were also measured in the municipal well. A Water flow and Nitrate transport Global Model (WNGM) was developed to simulate the impact of agricultural activities on nitrate concentrations in both the aquifer and municipal well. The WNGM first uses the Agriflux model to simulate vertical water and nitrate fluxes below the root zone for each of the seventy agricultural fields located within the capture zone of the municipal well. The WNGM then uses the HydroGeoSphere model to simulate three-dimensional variably-saturated groundwater flow and nitrate transport in the aquifer using water and nitrate fluxes computed with the Agriflux model as the top boundary conditions. The WNGM model was calibrated by reproducing water levels measured from 2005 to 2007 in the network of piezometers and nitrate concentrations measured in the municipal well from 1997 to 2007. The nitrate concentrations measured in the network of piezometers, however, showed greater variability than in the municipal well and could not be reproduced by the calibrated model. After calibration, the model was validated by successfully reproducing the decrease of nitrate concentrations observed in the municipal well in 2006 and 2007. Although it cannot predict nitrate concentrations in individual piezometers, the calibrated and validated WNGM can be used to assess the impact of changes in agricultural practices on global nitrate concentrations in the aquifer and in the municipal well.

Ground water quality in the Kathmandu valley of Nepal

A study was undertaken to assess the quality of groundwaters in the Kathmandu Valley, Nepal. The groundwater samples were randomly collected from shallow well, tube well, and deep-tube wells located at different places of Kathmandu, Lalitpur, and Bhaktapur districts in the Kathmandu valley. Physical, chemical, and microbiological parameters of the samples were evaluated to estimate the groundwater quality for drinking water. It was found that the groundwater in the valley is vulnerable to drink due to presence of iron and coliform bacteria. Iron was estimated to be much higher then the acceptable limit of World Health Organization (WHO) drinking-water quality guidelines (1.9 mg/L). Total coliform bacteria enumerated in groundwaters significantly exceeded the drinking-water quality standard and observed maximum coliform (267 CFU/100 mL) in shallow wells. The electrical conductivity and turbidity were found to be 875 μS/cm and 55 NTU, respectively, which are above the WHO recommendations for drinking water guidelines. However, pH value was measured within the acceptable limit. Arsenic, chloride, fluoride, and hardness concentrations were found to be in agreement with the recommendations of WHO drinking-water quality guidelines.

Occurrence of steroid hormones and antibiotics in shallow groundwater impacted by livestock waste control facilities

Wastewater impoundments at concentrated animal feeding operations (CAFOs) represent a potential source of veterinary pharmaceuticals and steroid hormone contamination to shallow groundwater. This study investigates the occurrence of seventeen veterinary pharmaceuticals and thirteen steroid hormones and hormone metabolites in lagoons and adjacent groundwater at operating swine and beef cattle facilities. These sites were chosen because subsurface geology and previous monitoring of nitrate, ammonia and chloride levels in shallow ground water strongly indicated direct infiltration, and as such represent worst cases for ground water contamination by waste water. Pharmaceutical compounds detected in samples obtained from cattle facilities include sulfamerazine; sulfamethazine; erythromycin; monensin; tiamulin; and sulfathiazole. Lincomycin; ractopamine; sulfamethazine; sulfathiazole; erythromycin; tiamulin and sulfadimethoxine were detected in wastewater samples obtained from swine facilities. Steroid hormones were detected less frequently than veterinary pharmaceuticals in this study. Estrone, testosterone, 4-androstenedione, and androsterone were detected in wastewater impoundments at concentrations ranging from 30 to 3600ng/L, while only estrone and testosterone were detected in groundwater samples at concentrations up to 390ng/L. The co-occurrence of veterinary pharmaceutical and steroid hormone contamination in groundwater at these locations and the correlation between pharmaceutical occurrence in lagoon wastewater and hydraulically downgradient groundwater indicates that groundwater underlying some livestock wastewater impoundments is susceptible to contamination by veterinary pharmaceuticals and steroid hormones originating in wastewater lagoons.

Land-use controls on sources and fate of nitrate in shallow groundwater of an agricultural area revealed by multiple environmental tracers

Sources and transformation processes of nitrate in groundwater from shallow aquifers were investigated in an agricultural area in the mid-western part of South Korea using a multi-tracer approach including δ²H and δ¹⁸O values of water, δ¹⁵N and δ¹⁸O values of nitrate, Cl/Br ratios and chlorofluorocarbons (CFCs). The study area was comprised of four land-use types with natural areas at higher altitudes, upland areas with fruit orchards, paddy fields and residential areas at lower elevations. The isotopic composition of water was suitable for distinguishing groundwater that had infiltrated in the higher elevation natural areas with lower δ²H and δ¹⁸O values from groundwater underneath paddy fields that was characterized by elevated δ²H and δ¹⁸O values due to evaporation. δ¹⁸O-H₂O values and Cl⁻ concentrations indicated that groundwater and contaminant sources were derived from three land-use types: natural areas, residential areas and paddy fields. Groundwater age determination based on CFCs showed that nitrate contamination of groundwater is primarily controlled by historic nitrogen loadings at least in areas with higher nitrate contamination. Nitrate sources were identified using the stable isotope composition of nitrate and Cl/Br ratios. Higher δ¹⁵N-NO₃⁻ values and Cl/Br ratios of 300 to 800 in residential areas indicated that waste water and septic effluents were major nitrate sources whereas lower δ¹⁵N-NO₃⁻ values and Cl/Br ratios of 100 to 700 in upland areas suggested that synthetic fertilizers constituted a major source of nitrate contamination of aquifers. With only few exceptions in the natural area, contributions of atmospheric nitrate were insignificant due to the resetting of δ¹⁸O-NO₃⁻ values via immobilization and re-mineralization of nitrate in the soil zone. In groundwater underneath paddy fields, 30% of samples had δ¹⁸O-NO₃⁻ values at least 2‰ higher than expected for nitrate formed by chemolithoautotrophic nitrification; these samples were also characterized by low DO and NO₃-N concentrations and elevated Cl and Mn concentrations indicating anthropogenic contamination and denitrification in the aquifer. These conditions were observed primarily in aquifers on floodplains. Statistical comparison between land-use groups revealed that Cl/Br ratios were more diagnostic for the impact of different land-use types on groundwater quality than stable isotope compositions of nitrate. This indicates that the former is an additional efficient tracer for the effect of land use on groundwater quality in agricultural areas. We conclude that the combination of groundwater age dating together with the use of chemical and isotopic parameters is a highly effective but yet underutilized approach for elucidating the sources and the fate of nitrate in aquifers in Asia.

A comparative evaluation of microalgae for the degradation of piggery wastewater under photosynthetic oxygenation

Two green microalgae (Scenedesmus obliquus and Chlorella sorokiniana), one cyanobacterium (Spirulina platensis), one euglenophyt (Euglena viridis) and two microalgae consortia were evaluated for their ability to support carbon, nitrogen and phosphorous removal in symbiosis with activated sludge bacteria during the biodegradation of four and eight times diluted piggery wastewater in batch tests. C. sorokiniana and E. viridis were capable of supporting the biodegradation of four and eight times diluted wastewater. On the other hand, while S. obliquus and the consortia isolated from a swine manure stabilization pond were only able to grow in eight times diluted wastewater, S. platensis and the consortium isolated from a high rate algal pond treating swine manure were totally inhibited regardless of the dilution applied. TOC removal efficiencies (RE) ranging from 42% to 55% and NH(4)(+)-RE from 21% to 39% were recorded in the tests exhibiting photosynthetic oxygenation. The similar oxygen production rates exhibited by the tested microalgae under autotrophic conditions (from 116 to 133mgO(2)L(-1)d(-1)) suggested that factors other than the photosynthetic oxygenation potential governed piggery wastewater biodegradation. Microalgal tolerance towards NH(3) was hypothesized as the key selection criterion. Further studies in a continuous algal-bacterial photobioreactor inoculated with C. sorokiniana, S. obliquus and S. platensis showed that C. sorokiniana, the species showing the highest NH(3)-tolerance, rapidly outcompeted the rest of the microalgae during the biodegradation of eight times diluted wastewater, achieving TOC and NH(4)(+)-RE comparable to those recorded in the batch biodegradation tests.

Long-term operation of high rate algal ponds for the bioremediation of piggery wastewaters at high loading rates

The performance of two 464-L high rate algal ponds (HRAPs) treating 20- and 10-folds diluted swine manure at 10 days of hydraulic residence time was evaluated under continental climatic conditions in Castilla y Leon (Spain) from January to October. Under optimum environmental conditions (from July to September), both HRAPs supported a stable and efficient carbon and nitrogen oxidation performance, with average COD and TKN removal efficiencies of 76+/-11% and 88+/-6%, respectively, and biomass productivities ranging from 21 to 28 g/m(2)d. Nitrification was identified as the main TKN removal mechanism at dissolved oxygen concentrations higher than 2mg/L (accounting for 80-86% of the TKN removed from January to May and for 54% from July to September). On the other hand, empirical evidences of a simultaneous nitrification-denitrification process were found at dissolved oxygen concentrations lower than 0.5mg/L (high organic loading rates). However, despite the achievement of excellent COD and nitrogen oxidation performance, phosphorous removal efficiencies lower than 10% were recorded in both HRAPs probably due to the high buffer capacity of the piggery wastewater treated (absence of abiotic pH-mediated PO(4)(3-) precipitation). Finally, a detailed monitorization of the dynamics of microalgae population revealed that the combination of moderate temperatures/solar irradiances and high organic loading rates, prevailing during late spring and summer, supported higher microalgae diversities than those found during winter conditions.

Reduction of indicator and pathogenic microorganisms in pig manure through fly ash and lime addition during alkaline stabilization

A pilot scale study was conducted to evaluate the effect of lime and alkaline coal fly ash (CFA) on the reduction of pathogens in pig manure during alkaline stabilization and suppression of re-growth during post-stabilization incubation. Pig manure was mixed with CFA at 25%, 33% and 50%, and a control without fly ash was maintained. To these manure-ash mixtures, lime was added at the rate of 2% or 4% and incubated for 8 days. During the incubation, the population of Salmonella, fecal coliforms, Escherichia coli, fecal Streptococcus and total bacteria were enumerated. After the alkaline stabilization process, the mixtures were incubated under green house condition to evaluate the re-growth of pathogens. During the 8-day alkaline stabilization, Salmonella, fecal coliforms, E. coli and fecal Streptococcus were completely devitalized in manure-ash-lime mixtures, whereas in the control, incubation reduced the pathogen and total bacterial population by 2-3 logs. Fecal streptococcus was destructed within 4 days of alkaline stabilization, whereas other pathogens needed 8 days for their destruction. During the incubation in green house, an increase in the population of the pathogens and total bacteria was observed. Results indicate that alkaline stabilization of pig manure with lime at 4% and CFA at 50% is effective in devitalizing the pathogens and reducing the post-stabilization re-growth.

Evaluation of swine-specific PCR assays used for fecal source tracking and analysis of molecular diversity of swine-specific "bacteroidales" populations

In this study, we evaluated the specificity, distribution, and sensitivity of Prevotella strain-based (PF163 and PigBac1) and methanogen-based (P23-2) PCR assays proposed to detect swine fecal pollution in environmental waters. The assays were tested against 222 fecal DNA extracts derived from target and nontarget animal hosts and against 34 groundwater and 15 surface water samples from five different sites. We also investigated the phylogenetic diversity of 1,340 "Bacteroidales" 16S rRNA gene sequences derived from swine feces, swine waste lagoons, swine manure pits, and waters adjacent to swine operations. Most swine fecal samples were positive for the host-specific Prevotella-based PCR assays (80 to 87%), while fewer were positive with the methanogen-targeted PCR assay (53%). Similarly, the Prevotella markers were detected more frequently than the methanogen-targeted assay markers in waters historically impacted with swine fecal contamination. However, the PF163 PCR assay cross-reacted with 23% of nontarget fecal DNA extracts, although Bayesian statistics suggested that it yielded the highest probability of detecting pig fecal contamination in a given water sample. Phylogenetic analyses revealed previously unknown swine-associated clades comprised of clones from geographically diverse swine sources and from water samples adjacent to swine operations that are not targeted by the Prevotella assays. While deeper sequencing coverage might be necessary to better understand the molecular diversity of fecal Bacteroidales species, results of sequence analyses supported the presence of swine fecal pollution in the studied watersheds. Overall, due to nontarget cross amplification and poor geographic stability of currently available host-specific PCR assays, development of additional assays is necessary to accurately detect sources of swine fecal pollution.

Microbial removal rates in subsurface media estimated from published studies of field experiments and large intact soil cores

Information about the microbial removal efficiencies of subsurface media is essential for assessing the risk of water contamination, estimating setback distances between disposal fields and receiving waters, and selecting suitable sites for wastewater reclamation. By analyzing published data from field experiments and large intact soil cores, an extensive database of microbial removal rates was established for a wide range of subsurface media. High microbial removal rates were found in volcanic soils, pumice sand, fine sand, and highly weathered aquifer rocks. Low removal rates were found in structured clayey soils, stony soils, coarse gravel aquifers, fractured rocks, and karst limestones. Removal rates were lower for enteroviruses than for other human viruses; for MS2 phage than for other phage species; for waste-associated microbes than for those cultivated in the laboratory; and for contaminated media than for uncontaminated media. Microbial removal rates are inversely correlated with infiltration rates and transport velocity. The assumption of first-order law, or a constant removal rate (when the transport scale reaches a representative elementary volume), is appropriate for most of field data analyzed. However 30% of the datasets (26 out of 87 pairs) are better described with the power law, implying reduced removal rates with transport distance. The latter is most prominent for organically contaminated media, especially in relatively fine aquifer media. The presence of organic matter, heterogeneity in microbial properties, change in solution chemistry, detachment, and physical straining, may have caused the discrepancies from the first-order law traditionally used in transport models for describing microbial removal.

Sulfamethoxazole contamination of a deep phreatic aquifer

Groundwater samples were obtained from the water table region of a phreatic aquifer (unsaturated zone depth up to 28 m) under land irrigated with wastewater effluents for about 5 decades and a relatively deep pumping well (109 m), used as a drinking water source till 2007, located downstream (1300 m) of wastewater effluent and sludge infiltration facilities. Sulfamethoxazole (SMX) concentrations in secondary effluents varied between 90 and 150 ng/L. SMX was extracted using SPE and was analyzed by HPLC-MS/MS. SMX (maximum concentration of 37 ng/L) was detected in the water table region, in two monitoring wells, after an unsaturated zone transport period of about 16 years. The maximum SMX concentration detected in the pumping well was of 20 ng/L. These results question wastewater effluent disposal strategies including the suitability of irrigation with effluents on the replenishment area of an aquifer supplying drinking water.

Effects of combined sewer overflow and stormwater on indicator bacteria concentrations in the Tama River due to the high population density of Tokyo Metropolitan area

The indicator bacteria (standard plate count, total coliform, and fecal coliform bacteria) concentrations have been investigated using six ambient habitats (population density, percent sewer penetration, stream flow rate (m(3)/sec), percent residential area, percent forest area and percent agricultural area) in the Tama River basin in Tokyo, Japan during June 2003 to January 2005. The downstream and tributary Tama River showed higher concentrations of TC and FC bacteria than the upstream waters, which exceeded an environmental quality standard for rivers and a bathing water quality criterion. It was estimated that combined sewer overflow (CSO) and stormwater effluents contributed -4-23% to the indicator bacteria concentrations of the Tama River. The results of multiple regression analyses show that the indicator bacteria concentrations of Tama River basin are significantly affected by population density. It is concluded that the Tama River received a significant bacterial contamination load originating from the anthropogenic source.

Effect of storage time on swine manure solid separation efficiency by screening

Confined animal feeding operations (CAFOs) have suffered considerable transformations since the last decade in Brazil, because of increasing of their production scale. Swine production is following this same trend, and the volume of manure produced and the form that is managed has a direct impact on houses air quality and efficiency of treatment systems. The objective of this work was to study the manure solid-liquid separation efficiency by screening, subject to different screen opening sizes and pit disposal time under tropical climate conditions. An ammoniacal nitrogen producing rate of 24 mg/L per storage day was observed and a decrease in screen separation efficiency in the first eight days of storage, obtained by solid group analysis. The storage time influenced directly the degradation of organic fraction indicated by the chemical oxygen demand increase overtime. The results suggest that the efficiency of solid-liquid separation is increased when carried out with the shortest storage time.

Salinity of animal manure and potential risk of secondary soil salinization through successive manure application

To enhance animal productivity and maximize economic returns, mineral salts are routinely added to animal feed worldwide. Salinity and ionic composition of animal manure from intensive poultry and livestock farms in Guangdong province were investigated. Field experiments were conducted for six successive crops of Brassica Parachinensis to evaluate the possibility of secondary soil salinization by successive application of chicken manure (CM) and pigeon manure (PM) to a garden soil. The concentration of total soluble salts (TSS), which were mainly composed of sulfate and chloride of potassium and sodium, averaged 49.0, 20.6 and 60.3 g.kg(- 1) in chicken, pig and pigeon manure, respectively. After three crops, successive application of CM and PM increased soil concentrations of TSS, Na(+), K(+), Mg(2+), SO(4)(2-), and Cl(-) with application rate, resulting in a rise in soil salinity from low to medium levels and a slight reduction in soil pH. After heavy rains during the last three crops, soil TSS was reduced considerably and pH showed a slight increase. Concentrations of Cl(-) and Mg(2+) increased and Ca(2+) decreased at the end of the experiment, all leading to changes in the ionic composition of soil salinity. Manure with higher ion concentrations appeared to play a more important role in affecting ionic composition of soil salinity. The results further suggest that even in a region with abundant rainfall like Guangzhou, there is still potential risk for secondary soil salinization when high rates of CM and PM are applied.

Antibiotic-resistant enterococci and fecal indicators in surface water and groundwater impacted by a concentrated Swine feeding operation

BACKGROUND

The nontherapeutic use of antibiotics in swine feed can select for antibiotic resistance in swine enteric bacteria. Leaking swine waste storage pits and the land-application of swine manure can result in the dispersion of resistant bacteria to water sources. However, there are few data comparing levels of resistant bacteria in swine manure-impacted water sources versus unaffected sources.

OBJECTIVES

The goal of this study was to analyze surface water and groundwater situated up and down gradient from a swine facility for antibiotic-resistant enterococci and other fecal indicators.

METHODS

Surface water and groundwater samples (n = 28) were collected up and down gradient from a swine facility from 2002 to 2004. Fecal indicators were isolated by membrane filtration, and enterococci (n = 200) were tested for susceptibility to erythromycin, tetracycline, clindamycin, virginiamycin, and vancomycin.

RESULTS

Median concentrations of enterococci, fecal coliforms, and Escherichia coli were 4- to 33-fold higher in down-gradient versus up-gradient surface water and groundwater. We observed higher minimal inhibitory concentrations for four antibiotics in enterococci isolated from down-gradient versus up-gradient surface water and groundwater. Elevated percentages of erythromycin- (p = 0.02) and tetracycline-resistant (p = 0.06) enterococci were detected in down-gradient surface waters, and higher percentages of tetracycline- (p = 0.07) and clindamycin-resistant (p < 0.001) enterococci were detected in down-gradient groundwater.

CONCLUSIONS

We detected elevated levels of fecal indicators and antibiotic-resistant enterococci in water sources situated down gradient from a swine facility compared with up-gradient sources. These findings provide additional evidence that water contaminated with swine manure could contribute to the spread of antibiotic resistance.

Development of a swine-specific fecal pollution marker based on host differences in methanogen mcrA genes

The goal of this study was to evaluate methanogen diversity in animal hosts to develop a swine-specific archaeal molecular marker for fecal source tracking in surface waters. Phylogenetic analysis of swine mcrA sequences compared to mcrA sequences from the feces of five animals (cow, deer, sheep, horse, and chicken) and sewage showed four distinct swine clusters, with three swine-specific clades. From this analysis, six sequences were chosen for molecular marker development and initial testing. Only one mcrA sequence (P23-2) showed specificity for swine and therefore was used for environmental testing. PCR primers for the P23-2 clone mcrA sequence were developed and evaluated for swine specificity. The P23-2 primers amplified products in P23-2 plasmid DNA (100%), pig feces (84%), and swine waste lagoon surface water samples (100%) but did not amplify a product in 47 bacterial and archaeal stock cultures and 477 environmental bacterial isolates and sewage and water samples from a bovine waste lagoon and a polluted creek. Amplification was observed in only one sheep sample out of 260 human and nonswine animal fecal samples. Sequencing of PCR products from pig feces demonstrated 100% similarity to pig mcrA sequence from clone P23-2. The minimal amount of DNA required for the detection was 1 pg for P23-2 plasmid, 1 ng for pig feces, 50 ng for swine waste lagoon surface water, 1 ng for sow waste influent, and 10 ng for lagoon sludge samples. Lower detection limits of 10(-6) g of wet pig feces in 500 ml of phosphate-buffered saline and 10(-4) g of lagoon waste in estuarine water were established for the P23-2 marker. This study was the first to utilize methanogens for the development of a swine-specific fecal contamination marker.

Monitoring and source tracking of tetracycline resistance genes in lagoons and groundwater adjacent to swine production facilities over a 3-year period

To monitor the dissemination of resistance genes into the environment, we determined the occurrence of tetracycline resistance (Tc(r)) genes in groundwater underlying two swine confinement operations. Monitoring well networks (16 wells at site A and 6 wells at site C) were established around the lagoons at each facility. Groundwater (n = 124) and lagoon (n = 12) samples were collected from the two sites at six sampling times from 2000 through 2003. Total DNA was extracted, and PCR was used to detect seven Tc(r) genes [tet(M), tet(O), tet(Q), tet(W), tet(C), tet(H), and tet(Z)]. The concentration of Tc(r) genes was quantified by real-time quantitative PCR. To confirm the Tc(r) gene source in groundwater, comparative analysis of tet(W) gene sequences was performed on groundwater and lagoon samples. All seven Tc(r) genes were continually detected in groundwater during the 3-year monitoring period at both sites. At site A, elevated detection frequency and concentration of Tc(r) genes were observed in the wells located down-gradient of the lagoon. Comparative analysis of tet(W) sequences revealed that the impacted groundwater contained gene sequences almost identical (99.8% identity) to those in the lagoon, but these genes were not found in background libraries. Novel sequence clusters and unique indigenous resistance gene pools were also found in the groundwater. Thus, antibiotic resistance genes in groundwater are affected by swine manure, but they are also part of the indigenous gene pool.

Tetracycline residues and tetracycline resistance genes in groundwater impacted by swine production facilities

Antibiotics are used at therapeutic levels to treat disease; at slightly lower levels as prophylactics; and at low, subtherapeutic levels for growth promotion and improvement of feed efficiency. Over 88% of swine producers in the United States gave antimicrobials to grower/finisher pigs in feed as a growth promoter in 2000. It is estimated that ca. 75% of antibiotics are not absorbed by animals and are excreted in urine and feces. The extensive use of antibiotics in swine production has resulted in antibiotic resistance in many intestinal bacteria, which are also excreted in swine feces, resulting in dissemination of resistance genes into the environment. To assess the impact of manure management on groundwater quality, groundwater samples have been collected near two swine confinement facilities that use lagoons for manure storage and treatment. Several key contaminant indicators - including inorganic ions, antibiotics, and antibiotic resistance genes - were analyzed in groundwater collected from the monitoring wells. Chloride, ammonium, potassium, and sodium were predominant inorganic constituents in the manure samples and served as indicators of groundwater contamination. Based on these analyses, shallow groundwater has been impacted by lagoon seepage at both sites. Liquid chromatography-mass spectroscopy (LC-MS) was used to measure the dissolved concentrations of tetracycline, chlortetracycline, and oxytetracycline in groundwater and manure. Although tetracyclines were regularly used at both facilities, they were infrequently detected in manure samples and then at relatively trace concentrations. Concentrations of all tetracyclines and their breakdown products in the groundwater sampled were generally less than 0.5 microg/L. Bacterial tetracycline resistance genes served as distinct genotypic markers to indicate the dissemination and mobility of antibiotic resistance genes that originated from the lagoons. Applying PCR to genomic DNA extracted from the lagoon and groundwater samples, four commonly occurring tetracycline (tet) resistance genes - tet(M), tet(O), tet(Q), and tet(W) - were detected. The detection frequency of tet genes was much higher in wells located closer to and down-gradient from the lagoons than in wells more distant from the lagoons. These results suggested that in the groundwater underlying both facilities tetracycline resistance genes exist and are somewhat persistent, but that the distribution and potentially the flux for each tet gene varied throughout the study period.

Removal of ammonium from aqueous solutions with volcanic tuff

This paper presents kinetic and equilibrium data concerning ammonium ion uptake from aqueous solutions using Romanian volcanic tuff. The influence of contact time, pH, ammonium concentration, presence of other cations and anion species is discussed. Equilibrium isotherms adequately fit the Langmuir and Freundlich models. The results showed a contact time of 3h to be sufficient to reach equilibrium and pH of 7 to be the optimum value. Adsorption capacities of 19 mg NH(4)(+)/g were obtained in multicomponent solutions (containing NH(4)(+), Zn(2+), Cd(2+), Ca(2+), Na(2+)). The presence of Zn and Cd at low concentrations did not decrease the ammonium adsorption capacity. Comparison of Romanian volcanic tuff with synthetic zeolites used for ammonium removal (5A, 13X and ZSM-5) was carried out. The removal efficiciency of ammonium by volcanic tuff were similar to those of zeolites 5A and 13X at low initial ammonium concentration, and much higher than those of zeolite ZSM-5.