1
|
Zhong L, Wu T, Ding J, Xu W, Yuan F, Liu BF, Zhao L, Li Y, Ren NQ, Yang SS. Co-composting of faecal sludge and carbon-rich wastes in the earthworm's synergistic cooperation system: Performance, global warming potential and key microbiome. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 857:159311. [PMID: 36216047 DOI: 10.1016/j.scitotenv.2022.159311] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2022] [Revised: 09/21/2022] [Accepted: 10/04/2022] [Indexed: 06/16/2023]
Abstract
Composting is an effective alternative for recycling faecal sludge into organic fertilisers. A microflora-earthworm (Eisenia fetida) synergistic cooperation system was constructed to enhance the composting efficiency of faecal sludge. The impact of earthworms and carbon-rich wastes (rice straw (RS) and sawdust (S)) on compost properties, greenhouse gas emissions, and key microbial species of composting were evaluated. The addition of RS or S promoted earthworm growth and reproduction. The earthworm-based system reduced the volatile solid of the final substrate by 13.19-16.24 % and faecal Escherichia coli concentrations by 1.89-3.66 log10 cfu/g dry mass compared with the earthworm-free system. The earthworm-based system increased electrical conductivity by 0.322-1.402 mS/cm and reduced C/N by 56.16-64.73 %. The NH4+:NO3- ratio of the final faecal sludge and carbon-rich waste was <0.16. The seed germination index was higher than 80 %. These results indicate that earthworms contribute to faecal sludge maturation. Earthworm addition reduced CO2 production. The simultaneous addition of earthworms and RS system (FRS2) resulted in the lowest global warming potential (GWP). The microbial diversity increased significantly over time in the RS-only system, whereas it initially increased and later decreased in the FRS2 system. Cluster analysis revealed that earthworms had a more significant impact on the microbial community than the addition of carbon-rich waste. Co-occurrence networks for earthworm-based systems were simple than those for earthworm-free systems, but the major bacterial genera were more complicated. Highly abundant key species (norank_f_Chitinophagaceae and norank_f_Gemmatimonadaceae) are closely related. Microbes may be more cooperative than competitive, facilitating the conversion of carbon and nitrogen in earthworm-based systems. This work has demonstrated that using earthworms is an effective approach for promoting the efficiency of faecal sludge composting and reducing GWP.
Collapse
Affiliation(s)
- Le Zhong
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Tong Wu
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Jie Ding
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China.
| | - Wei Xu
- General Water of China Co., Ltd., Beijing 100022, China
| | - Fang Yuan
- General Water of China Co., Ltd., Beijing 100022, China
| | - Bing-Feng Liu
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Lei Zhao
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Yan Li
- School of Environmental Science and Engineering, Yancheng Institute of Technology, Yancheng, 224051, China
| | - Nan-Qi Ren
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Shan-Shan Yang
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China.
| |
Collapse
|
2
|
Kelova ME, Ali AM, Eich-Greatorex S, Dörsch P, Kallenborn R, Jenssen PD. Small-scale on-site treatment of fecal matter: comparison of treatments for resource recovery and sanitization. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2021; 28:63945-63964. [PMID: 33666847 PMCID: PMC8610962 DOI: 10.1007/s11356-021-12911-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 02/08/2021] [Indexed: 06/12/2023]
Abstract
On-site small-scale sanitation is common in rural areas and areas without infrastructure, but the treatment of the collected fecal matter can be inefficient and is seldom directed to resource recovery. The aim of this study was to compare low-technology solutions such as composting and lactic acid fermentation (LAF) followed by vermicomposting in terms of treatment efficiency, potential human and environmental risks, and stabilization of the material for reuse in agriculture. A specific and novel focus of the study was the fate of native pharmaceutical compounds in the fecal matter. Composting, with and without the addition of biochar, was monitored by temperature and CO2 production and compared with LAF. All treatments were run at three different ambient temperatures (7, 20, and 38°C) and followed by vermicomposting at room temperature. Materials resulting from composting and LAF were analyzed for fecal indicators, physicochemical characteristics, and residues of ten commonly used pharmaceuticals and compared to the initial substrate. Vermicomposting was used as secondary treatment and assessed by enumeration of Escherichia coli, worm density, and physicochemical characteristics. Composting at 38°C induced the highest microbial activity and resulted in better stability of the treated material, higher N content, lower numbers of fecal indicators, and less pharmaceutical compounds as compared to LAF. Even though analysis of pH after LAF suggested incomplete fermentation, E. coli cell numbers were significantly lower in all LAF treatments compared to composting at 7°C, and some of the anionic pharmaceutical compounds were detected in lower concentrations. The addition of approximately 5 vol % biochar to the composting did not yield significant differences in measured parameters. Vermicomposting further stabilized the material, and the treatments previously composted at 7°C and 20°C had the highest worm density. These results suggest that in small-scale decentralized sanitary facilities, the ambient temperatures can significantly influence the treatment and the options for safe reuse of the material.
Collapse
Affiliation(s)
- Mariya E. Kelova
- Faculty of Environmental Sciences and Natural Resource Management (MINA), Norwegian University of Life Sciences (NMBU), Fougnerbakken 3, NO-1433 Ås, Norway
| | - Aasim M. Ali
- Faculty of Chemistry, Biotechnology and Food Science (KBM), Norwegian University of Life Sciences (NMBU), Chr. M. Falsens vei 1, NO-1433 Ås, Norway
- Department of Contaminants and Biohazards, Institute of Marine Research, NO-5817 Bergen, Norway
| | - Susanne Eich-Greatorex
- Faculty of Environmental Sciences and Natural Resource Management (MINA), Norwegian University of Life Sciences (NMBU), Fougnerbakken 3, NO-1433 Ås, Norway
| | - Peter Dörsch
- Faculty of Environmental Sciences and Natural Resource Management (MINA), Norwegian University of Life Sciences (NMBU), Fougnerbakken 3, NO-1433 Ås, Norway
| | - Roland Kallenborn
- Faculty of Chemistry, Biotechnology and Food Science (KBM), Norwegian University of Life Sciences (NMBU), Chr. M. Falsens vei 1, NO-1433 Ås, Norway
| | - Petter D. Jenssen
- Faculty of Environmental Sciences and Natural Resource Management (MINA), Norwegian University of Life Sciences (NMBU), Fougnerbakken 3, NO-1433 Ås, Norway
| |
Collapse
|
3
|
Lourenço N, Nunes LM. Review of Dry and Wet Decentralized Sanitation Technologies for Rural Areas: Applicability, Challenges and Opportunities. ENVIRONMENTAL MANAGEMENT 2020; 65:642-664. [PMID: 32123966 DOI: 10.1007/s00267-020-01268-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2019] [Accepted: 02/07/2020] [Indexed: 06/10/2023]
Abstract
This paper reviews decentralized sanitation technologies comparing dry and wet solutions currently available, discussing their operational requirements, applicability, effluent output quality, efficiencies, environmental impacts, costs, challenges, as well as their advantages and implementation difficulties. Sanitation technologies vary from conventional centralized systems, typically used on urban areas, to decentralized systems, more common in sparse dwellings and small communities of rural areas. Compared with centralized sanitation, decentralized sanitation is being progressively considered as more sustainable solution. Most do not require energy or expensive or sophisticated operation, being easy to adapt to different geographic contexts. A general lack of consistent regulatory control over most dry rudimentary systems and primary treatment systems may compromise water quality and human health. In the future, a mix of new policies and accurate accounting of the location, performance, and degree of failure of such systems should be performed. However, forcing users and communities to face the capital, operational, or repairing costs may be challenging. Since many of the discussed technologies may be important sources of contamination with nutrients, pathogens and toxic chemicals, new opportunities are still open, which include the conversion of dry rudimentary systems into dry controlled systems.
Collapse
Affiliation(s)
- N Lourenço
- FUTURAMB® and Faculty of Sciences and Technology, University of Algarve, Faro, Portugal.
| | - L M Nunes
- Faculty of Sciences and Technology, Civil Engineering Research and Innovation for Sustainability Center, University of Algarve, Faro, Portugal
| |
Collapse
|
4
|
Huang K, Xia H, Zhang Y, Li J, Cui G, Li F, Bai W, Jiang Y, Wu N. Elimination of antibiotic resistance genes and human pathogenic bacteria by earthworms during vermicomposting of dewatered sludge by metagenomic analysis. BIORESOURCE TECHNOLOGY 2020; 297:122451. [PMID: 31787516 DOI: 10.1016/j.biortech.2019.122451] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 11/15/2019] [Accepted: 11/17/2019] [Indexed: 05/15/2023]
Abstract
This study used a metagenomic approach to investigate the effects of earthworms on ARGs and HPB during the vermicomposting of dewatered sludge. Results showed that 139 types of ARGs were found in sludge vermicompost, affiliated to 30 classes. Compared with the control, the total abundance of ARGs in sludge vermicompost decreased by 41.5%. Moreover, the types and sequences of plasmids and integrons were also decreased by vermicomposting. Proteobacteria and Actinobacteria were the most dominant hosts of ARGs in sludge vermicompost. In addition, earthworms reduced the total HPB abundance and modified their diversity, thus leading to higher abundance of Enterobacteriaceae in sludge vermicompost. However, the sludge vermicompost was still ARG and HPB enriched, indicating a remaining environmental risk for agricultural purpose. The observed change of microbial community and the reduction of mobile genetic elements caused by earthworm activity are the main reasons for the alleviation of ARG pollution during vermicomposting.
Collapse
Affiliation(s)
- Kui Huang
- School of Environmental and Municipal Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China.
| | - Hui Xia
- School of Environmental and Municipal Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China
| | - Yingying Zhang
- School of Environmental and Municipal Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China
| | - Jianhui Li
- School of Environmental and Municipal Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China
| | - Guangyu Cui
- State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092, China
| | - Fusheng Li
- River Basin Research Center, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Wei Bai
- School of Environmental and Municipal Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China
| | - Yufeng Jiang
- School of Environmental and Municipal Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China
| | - Nan Wu
- School of Environmental and Municipal Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China
| |
Collapse
|
5
|
Oarga-Mulec A, Hanssen JF, Jenssen PD, Bulc TG. A comparison of various bulking materials as a supporting matrix in composting blackwater solids from vacuum toilets. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2019; 243:78-87. [PMID: 31082754 DOI: 10.1016/j.jenvman.2019.05.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 04/03/2019] [Accepted: 05/02/2019] [Indexed: 06/09/2023]
Abstract
This study discusses the influence of six bulking materials (peat, bark, oat husks, sawdust, food waste, and wheat bran) on the composting of blackwater solids (feces, urine and toilet paper) from low flush vacuum toilets (0.8 L/flush). The focus was on faecal indicator reduction, nutrient recycling, and carbon dioxide and methane emissions. In a composting experiment lasting 60 days, bulking materials were combined and mixed with blackwater solids, composted without stirring and with controlled aeration in a bench scale experiment. The bulking materials combination of oat husks, wheat bran and bark and of oat husks and wheat bran composted with blackwater solids showed the best results in terms of faecal indicator reduction (2.8 log10 reduction of Escherichia coli and 3.2 log10 reduction of faecal streptococci, respectively). Oat husks, bark and wheat bran combination had the smallest nutrient losses of 7.5% total nitrogen, 3.8% total phosphorus and 28% total potassium, while the highest accumulation in total phosphorus was 76.4% occurred in the mixture with oat husks and wheat bran. Peat and food waste improved the sorption of ammonia. The highest methane emissions (average 15.4%) were detected after 28 days of composting in the mixture with bran and food waste. Methane and carbon dioxide levels decreased in all the mixtures towards the end of composting indicating high organic matter degradation. Our findings show that a variety of natural and inexpensive materials can be used and adapted when composing blackwater in remote and sensitive areas.
Collapse
Affiliation(s)
- Andreea Oarga-Mulec
- Slovenian National Building and Civil Engineering Institute, Dimiceva ulica 12, SI-1000, Ljubljana, Slovenia; School of Environmental Sciences, University of Nova Gorica, Vipavska 13, SI-5000, Nova Gorica, Slovenia.
| | - Jon Fredrik Hanssen
- Department of Environmental Sciences, Norwegian University of Life Sciences, 5003, N-1432, Aas, Norway
| | - Petter D Jenssen
- Department of Environmental Sciences, Norwegian University of Life Sciences, 5003, N-1432, Aas, Norway
| | - Tjaša Griessler Bulc
- Institute of Sanitary Engineering, Faculty of Civil and Geodetic Engineering, University of Ljubljana, Hajdrihova 28, SI-1000, Ljubljana, Slovenia; Department of Sanitary Engineering, Faculty of Health Sciences, University of Ljubljana, Zdravstvena pot 5, SI-1000, Ljubljana, Slovenia
| |
Collapse
|
6
|
Nasri B, Brun F, Fouché O. Evaluation of the quality and quantity of compost and leachate from household waterless toilets in France. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2019; 26:2062-2078. [PMID: 29105039 DOI: 10.1007/s11356-017-0604-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 10/24/2017] [Indexed: 06/07/2023]
Abstract
One of the most undesired wastes is the human excreta due to the socio-environmental pressure. Otherwise, the nutriments contained in human excreta could be used as fertilizers to enrich the soil. Familial waterless litter composting toilets (FWLCT) are an alternative for locations where a centralized sewerage network cannot be provided or where there is a lack of standard urban infrastructure including roads, electricity, and water supply. The scientific researches on the composting techniques, the methods of control of the composting processors, and the rate of produced leachate are very limited. In this research, the composting systems included a feces and urine collection device. In each passage, the litter (carbonaceous material) is added to the excreta. Regularly, the buckets were emptied into a composting device located outside the house to which an additional portion of carbonaceous materials can be added. Monitoring was carried out on five rural and one urban familial composting areas in France for 1.5 years. The physiochemical and microbiological properties of the compost and leachate have been monitored and measured in compliance with the protocols. The results show that one of the main problems of this system of human excreta treatment is that the composting process does not achieve a significant rise in temperature and does not allow reaching the optimum temperatures (> 50 °C). Otherwise, from an agronomic point of view, the obtained compost is not rich enough in nutriments to be a good compost as soil fertilizer. But it can be used as a soil conditioner. The average leachate flux from the composters is 1.79 L/day. Because of the very short stay time in the piles, the leachate is contaminated by harmful bacteria and should be treated by another sanitation system.
Collapse
Affiliation(s)
- Behzad Nasri
- GeF lab., Geomatique & Foncier, EA 4630, Le Cnam, 2 rue Conté, 75003, Paris, France.
| | - Florent Brun
- Toilettes Du Monde, 28 place du docteur Bourdongle, 26110, Nyons, France
| | - Olivier Fouché
- GeF lab., Geomatique & Foncier, EA 4630, Le Cnam, 2 rue Conté, 75003, Paris, France
| |
Collapse
|
7
|
Williams LE, Kleinschmidt CE, Mecca S. Bacterial communities in the digester bed and liquid effluent of a microflush composting toilet system. PeerJ 2018; 6:e6077. [PMID: 30564526 PMCID: PMC6286801 DOI: 10.7717/peerj.6077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 11/05/2018] [Indexed: 12/02/2022] Open
Abstract
Lack of access to clean water and sanitation is a major factor impacting public health in communities worldwide. To address this, the S-Lab at Providence College and the Global Sustainable Aid Project developed a microflush composting toilet system to isolate and treat human waste. Solid waste is composted within a filter-digester bed via an aerobic process involving microbes and invertebrates. Liquid waste may be sanitized by solar disinfection (SODIS) or slow sand filtration (SSF). Here, we used 16S rRNA amplicon sequencing of samples from a scaled-down test version of the system to better understand the bacterial component of the toilet system. Immediately after fecal matter was deposited in the test system, the bacterial community of the filter-digester bed at the site of deposition resembled that of the human gut at both the phylum and genus level, which was expected. Genus-level analysis of filter-digester bed samples collected over the next 30 days from the site of deposition showed reduced or undetectable levels of fecal-associated taxa, with the exception of Clostridium XI, which persisted at low abundance throughout the sampling period. Starting with the sample collected on day 4, the bacterial community of the filter-digester bed at the site of deposition was dominated by bacterial taxa commonly associated with environmental sources, reflecting a major shift in bacterial community composition. These data support the toilet system’s capacity for processing solid human waste. We also analyzed how SODIS and SSF sanitization methods affected the bacterial community composition of liquid effluent collected on day 15 from the test system. Untreated and treated liquid effluent samples were dominated by Proteobacteria. At the genus level, the bacterial community of the untreated effluent included taxa commonly associated with environmental sources. In the SODIS-treated effluent, these genera increased in abundance, whereas in the SSF-treated effluent, they were greatly reduced or undetectable. By analyzing operational taxonomic units that were unclassified at the genus level, we observed that SSF appears to introduce new taxa into the treated effluent, likely from the biological film of microbes and small animals that constitutes the key element of SSF. These data will inform continued development of liquid waste handling strategies for the toilet system. Using the test system as an indicator of the performance of the full-scale version, we have shown the effectiveness of the microflush composting toilet system for containing and eliminating gut-associated bacteria, thereby improving sanitation and contributing to better public health in rural and peri-urban communities.
Collapse
Affiliation(s)
| | - Claire E Kleinschmidt
- Department of Biology, Providence College, Providence, RI, USA.,Department of Engineering-Physics-Systems, Providence College, Providence, RI, USA
| | - Stephen Mecca
- Department of Engineering-Physics-Systems, Providence College, Providence, RI, USA
| |
Collapse
|
8
|
Lv B, Xing M, Yang J. Exploring the effects of earthworms on bacterial profiles during vermicomposting process of sewage sludge and cattle dung with high-throughput sequencing. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2018; 25:12528-12537. [PMID: 29464602 DOI: 10.1007/s11356-018-1520-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 02/08/2018] [Indexed: 05/15/2023]
Abstract
This study aims to reveal the effects of earthworms (Eisenia fetida) on bacterial profiles during the vermicomposting process of sewage sludge and cattle dung with the high-throughput sequencing technology. The earthworms could accelerate organic degradation and improve the stabilization process. Moreover, the addition of earthworms not only affected the bacterial numbers, but also increased the bacterial community diversity. The activity of earthworms had significant effects on the bacterial community structure as the bacterial community was clearly different between the vermicomposting and the control treatment. Furthermore, the earthworms affected the physical and chemical properties of substrates, thus promoting the growth of some microorganisms, such as Flavobacteria, Acidbacteria, and Planctomycetes. Earthworms largely inhibited the growth of various human pathogenic bacteria. In summary, earthworms significantly affected the bacterial community in vermicomposting and it could be applied as an authentically effective technique for the stabilization of organic wastes.
Collapse
Affiliation(s)
- Baoyi Lv
- Institute of Biofilm Technology, Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China.
- College of Ocean Science and Engineering, Shanghai Maritime University, Shanghai, 201306, China.
| | - Meiyan Xing
- Institute of Biofilm Technology, Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China.
| | - Jian Yang
- Institute of Biofilm Technology, Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China
| |
Collapse
|
9
|
Soobhany N. Preliminary evaluation of pathogenic bacteria loading on organic Municipal Solid Waste compost and vermicompost. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2018; 206:763-767. [PMID: 29161678 DOI: 10.1016/j.jenvman.2017.11.029] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2017] [Revised: 10/26/2017] [Accepted: 11/10/2017] [Indexed: 06/07/2023]
Abstract
The use of composts or vermicomposts derived from organic fraction of Municipal Solid Waste (OFMSW) brought about certain disagreement in terms of high level of bacterial pathogens, thereby surpassing the legal restrictions. This preliminary study was undertaken to compare the evolution of pathogenic bacteria on OFMSW compost against vermicompost (generated by Eudrilus eugeniae) with promises of achieving sanitation goals. Analysis to quality data showed that OFMSW vermicomposting caused a moderately higher reduction in total coliforms in contrast to composting. E. coli in OFMSW composts was found to be in the range of 4.72-4.96 log10 CFU g-1 whilst on a clear contrary, E. coli was undetectable in the final vermicomposts (6.01-6.14 logs of reduction) which might be explained by the involvement of the digestive processes in worms' guts. Both OFMSW composts and vermicomposts generated Salmonella-free products which were acceptable for agricultural usage and soil improvement. In comparison to compost, the analysis of this research indicated that earthworm activity can effectively destroy bacterial pathogenic load in OFMSW vermicomposts. But still, this study necessitates extra research in order to comprehend the factors that direct pathogenic bacteria in vermicomposting and earthworm-free decomposition systems.
Collapse
Affiliation(s)
- Nuhaa Soobhany
- Department of Chemical & Environmental Engineering, Faculty of Engineering, University of Mauritius, Réduit, Mauritius.
| |
Collapse
|
10
|
Singh A, Singh GS. Vermicomposting: A sustainable tool for environmental equilibria. ACTA ACUST UNITED AC 2018. [DOI: 10.1002/tqem.21509] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Archana Singh
- Institute of Environment and Sustainable Development; Banaras Hindu University; Varanasi, Uttar Pradesh India
| | - Gopal Shankar Singh
- Institute of Environment and Sustainable Development; Banaras Hindu University; Varanasi, Uttar Pradesh India
| |
Collapse
|
11
|
Swati A, Hait S. A Comprehensive Review of the Fate of Pathogens during Vermicomposting of Organic Wastes. JOURNAL OF ENVIRONMENTAL QUALITY 2018; 47:16-29. [PMID: 29415111 DOI: 10.2134/jeq2017.07.0265] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Management of both municipal and industrial organic wastes remains a major threat to biota and the environment due to the presence of pathogens in abundance. Vermicomposting employing earthworms is increasingly gaining attention as a sustainable and ecofriendly technique to transform and sanitize a variety of organic wastes into nutrient-rich biofertilizer. Although considerable research has been undertaken to show that vermicomposting can significantly reduce pathogenic contents, there is little effort to summarize the various mechanisms responsible for it. With the aim to assess the fate of pathogens during vermicomposting of various organic wastes, this article provides a comprehensive summary on the occurrence of pathogens in a variety of wastes vis-à-vis pathogens standards, the efficacy of the process for pathogen reduction, and current knowledge of the plausible mechanisms involved. It is evident from the present study that earthworms and endosymbiotic microbes during vermicomposting tend to eliminate pathogens by enhancing enzymatic activities in both gut- and cast-associated processes. Pathogen reduction during vermicomposting can be plausibly attributed to direct actions like microbial inhibition due to intestinal enzymatic action, and secretion of coelomic fluids with antibacterial properties, as well as indirect actions like stimulation of endemic microbes leading to competition and antagonism, and aeration by burrowing activity. Further, the pathogen reduction during vermicomposting is largely selective, and earthworms exert a differential effect according to the earthworm species and whether the pathogen considered is Gram-positive or -negative, owing to its cell wall composition. However, further research is necessary to understand the exact mechanisms involved for pathogen reduction during vermistabilization of municipal and industrial organic wastes.
Collapse
|
12
|
Soobhany N, Mohee R, Garg VK. Inactivation of bacterial pathogenic load in compost against vermicompost of organic solid waste aiming to achieve sanitation goals: A review. WASTE MANAGEMENT (NEW YORK, N.Y.) 2017; 64:51-62. [PMID: 28302524 DOI: 10.1016/j.wasman.2017.03.003] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2016] [Revised: 03/02/2017] [Accepted: 03/02/2017] [Indexed: 05/15/2023]
Abstract
Waste management strategies for organic residues, such as composting and vermicomposting, have been implemented in some developed and developing countries to solve the problem of organic solid waste (OSW). Yet, these biological treatment technologies do not always result in good quality compost or vermicompost with regards to sanitation capacity owing to the presence of bacterial pathogenic substances in objectionable concentrations. The presence of pathogens in soil conditioners poses a potential health hazard and their occurrence is of particular significance in composts and/or vermicomposts produced from organic materials. Past and present researches demonstrated a high-degree of agreement that various pathogens survive after the composting of certain OSW but whether similar changes in bacterial pathogenic loads arise during vermitechnology has not been thoroughly elucidated. This review garners information regarding the status of various pathogenic bacteria which survived or diffused after the composting process compared to the status of these pathogens after the vermicomposting of OSW with the aim of achieving sanitation goals. This work is also indispensable for the specification of compost quality guidelines concerning pathogen loads which would be specific to treatment technology. It was hypothesized that vermicomposting process for OSW can be efficacious in sustaining the existence of pathogenic organisms most specifically; human pathogens under safety levels. In summary, earthworms can be regarded as a way of obliterating pathogenic bacteria from OSW in a manner equivalent to earthworm gut transit mechanism which classifies vermicomposting as a promising sanitation technique in comparison to composting processes.
Collapse
Affiliation(s)
- Nuhaa Soobhany
- Department of Chemical and Environmental Engineering, Faculty of Engineering, University of Mauritius, Reduit 80837, Mauritius.
| | - Romeela Mohee
- Office of Vice Chancellor, University of Mauritius, Reduit 80837, Mauritius
| | - Vinod Kumar Garg
- Centre for Environmental Science and Technology, Central University of Punjab, Bathinda 155001, Punjab, India
| |
Collapse
|
13
|
Hénault-Ethier L, Martin VJJ, Gélinas Y. Persistence of Escherichia coli in batch and continuous vermicomposting systems. WASTE MANAGEMENT (NEW YORK, N.Y.) 2016; 56:88-99. [PMID: 27499290 DOI: 10.1016/j.wasman.2016.07.033] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 07/21/2016] [Accepted: 07/25/2016] [Indexed: 06/06/2023]
Abstract
Vermicomposting is a biooxidation process in which epigeicearthworms act in synergy with microbial populations to degrade organic matter. Vermicomposting does not go through a thermophilic stage as required by North American legislations for pathogen eradication. We examined the survival of a Green Fluorescent Protein (GFP) labeled Escherichia coli MG1655 as a model for the survival of pathogenic bacteria in both small-scale batch and medium-scale continuously-operated systems to discern the influence of the earthworm Eisenia fetida, nutrient content and the indigenous vermicompost microbial community on pathogen abundance. In batch systems, the microbial community had the greatest influence on the rapid decline of E. coli populations, and the effect of earthworms was only visible in microbially-impoverishedvermicomposts. No significant earthworm density-dependent relationship was observed on E. coli survival under continuous operation. E. coli numbers decreased below the US EPA compost sanitation guidelines of 10(3)Colony Forming Units (CFU)/g (dry weight) within 18-21days for both the small-scale batch and medium-scale continuous systems, but it took up to 51days without earthworms and with an impoverished microbial community to reach the legal limit. Nutrient replenishment (i.e. organic carbon) provided by continuous feed input did not appear to extend E. coli survival. In fact, longer survival of E. coli was noticed in treatments where less total and labile sugars were available, suggesting that sugars may support potentially antagonist bacteria in the vermicompost. Total N, pH and humidity did not appear to affect E. coli survival. Several opportunistic human pathogens may be found in vermicompost, and their populations are likely kept in check by antagonists.
Collapse
Affiliation(s)
- Louise Hénault-Ethier
- Department of Biology, Concordia University, Montreal, QC, Canada; GEOTOP Research Center, Montreal, QC, Canada
| | | | - Yves Gélinas
- GEOTOP Research Center, Montreal, QC, Canada; Department of Chemistry and Biochemistry, Concordia University, Montreal, QC, Canada.
| |
Collapse
|
14
|
Wood A, Blackhurst M, Hawkins T, Xue X, Ashbolt N, Garland J. Cost-effectiveness of nitrogen mitigation by alternative household wastewater management technologies. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2015; 150:344-354. [PMID: 25575282 DOI: 10.1016/j.jenvman.2014.10.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Accepted: 10/10/2014] [Indexed: 06/04/2023]
Abstract
Household wastewater, especially from conventional septic systems, is a major contributor to nitrogen pollution. Alternative household wastewater management technologies provide similar sewerage management services but their life cycle costs and nitrogen flow implications remain uncertain. This paper addresses two key questions: (1) what are the total costs, nitrogen mitigation potential, and cost-effectiveness of a range of conventional and alternative municipal wastewater treatment technologies, and (2) what uncertainties influence these outcomes and how can we improve our understanding of these technologies? We estimate a household nitrogen mass balance for various household wastewater treatment systems and combine this mass balance with life cycle cost assessment to calculate the cost-effectiveness of nitrogen mitigation, which we define as nitrogen removed from the local watershed. We apply our methods to Falmouth, MA, where failing septic systems have caused heightened eutrophication in local receiving water bodies. We find that flushing and dry (composting) urine-diversion toilets paired with conventional septic systems for greywater management demonstrate the lowest life cycle cost and highest cost-effectiveness (dollars per kilogram of nitrogen removed from the watershed). Composting toilets are also attractive options in some cases, particularly best-case nitrogen mitigation. Innovative/advanced septic systems designed for high-level nitrogen removal are cost-competitive options for newly constructed homes, except at their most expensive. A centralized wastewater treatment plant is the most expensive and least cost-effective option in all cases. Using a greywater recycling system with any treatment technology increases the cost without adding any nitrogen removal benefits. Sensitivity analysis shows that these results are robust considering a range of cases and uncertainties.
Collapse
Affiliation(s)
- Alison Wood
- The University of Texas at Austin, Dept. of Civil, Architectural, and Environmental Engineering, 301 E. Dean Keeton St. C8600, Austin, TX 78712-8600, United States.
| | - Michael Blackhurst
- The University of Texas at Austin, 301 E. Dean Keeton St. C2100, Austin, TX 78712-2100, United States
| | - Troy Hawkins
- U.S. Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, 26 W. Martin Luther King Drive, Cincinnati, OH, 45268, United States
| | - Xiaobo Xue
- ORISE Research Fellow, U.S. Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, 26 W. Martin Luther King Drive, Cincinnati, OH 45268, United States
| | - Nicholas Ashbolt
- U.S. Environmental Protection Agency, Office of Research and Development, National Exposure Research Laboratory, 26 W. Martin Luther King Drive, Cincinnati, OH, 45268, United States
| | - Jay Garland
- U.S. Environmental Protection Agency, Office of Research and Development, Microbiological and Chemical Exposure Assessment Research Division, 26 W. Martin Luther King Drive, Cincinnati, OH, 45268, United States
| |
Collapse
|
15
|
Anand CK, Apul DS. Composting toilets as a sustainable alternative to urban sanitation--a review. WASTE MANAGEMENT (NEW YORK, N.Y.) 2014; 34:329-343. [PMID: 24268916 DOI: 10.1016/j.wasman.2013.10.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Revised: 07/09/2013] [Accepted: 10/10/2013] [Indexed: 06/02/2023]
Abstract
In today's flush based urban sanitation systems, toilets are connected to both the centralized water and wastewater infrastructures. This approach is not a sustainable use of our water and energy resources. In addition, in the U.S., there is a shortfall in funding for maintenance and upgrade of the water and wastewater infrastructures. The goal of this paper was to review the current knowledge on composting toilets since this technology is decentralized, requires no water, creates a value product (fertilizer) and can possibly reduce the burden on the current infrastructure as a sustainable sanitation approach. We found a large variety of composting toilet designs and categorized the different types of toilets as being self contained or central; single or multi chamber; waterless or with water/foam flush, electric or non-electric, and no-mix or combined collection. Factors reported as affecting the composting process and their optimum values were identified as; aeration, moisture content (50-60%), temperature (40-65°C), carbon to nitrogen ratio (25-35), pH (5.5-8.0), and porosity (35-50%). Mass and energy balance models have been created for the composting process. However there is a literature gap in the use of this knowledge in design and operation of composting toilets. To evaluate the stability and safety of compost for use as fertilizer, various methods are available and the temperature-time criterion approach is the most common one used. There are many barriers to the use of composting toilets in urban settings including public acceptance, regulations, and lack of knowledge and experience in composting toilet design and operation and program operation.
Collapse
Affiliation(s)
- Chirjiv K Anand
- Department of Civil Engineering, The University of Toledo, MS 307, 2801 W. Bancroft St., Toledo, OH 43606, USA.
| | - Defne S Apul
- Department of Civil Engineering, The University of Toledo, MS 307, 2801 W. Bancroft St., Toledo, OH 43606, USA.
| |
Collapse
|
16
|
Hill GB, Baldwin SA, Vinnerås B. Evaluation of Solvita compost stability and maturity tests for assessment of quality of end-products from mixed latrine style compost toilets. WASTE MANAGEMENT (NEW YORK, N.Y.) 2013; 33:1602-1606. [PMID: 23647950 DOI: 10.1016/j.wasman.2013.03.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Revised: 03/15/2013] [Accepted: 03/29/2013] [Indexed: 06/02/2023]
Abstract
It is challenging and expensive to monitor and test decentralized composting toilet systems, yet critical to prevent the mismanagement of potentially harmful and pathogenic end-product. Recent studies indicate that mixed latrine composting toilets can be inhibited by high ammonia content, a product of urea hydrolysis. Urine-diverting vermicomposting toilets are better able to accomplish the goals of remote site human waste management by facilitating the consumption of fecal matter by earthworms, which are highly sensitive to ammonia. The reliability of Solvita compost stability and maturity tests were evaluated as a means of determining feedstock suitability for vermicomposting (ammonia) and end-product stability/completeness (carbon dioxide). A significant linear regression between Solvita ammonia and free ammonia gas was found. Solvita ranking of maturity did not correspond to ranking assigned by ammonium:nitrate standards. Solvita ammonia values 4 and 5 contained ammonia levels below earthworm toxicity limits in 80% and 100% of samples respectively indicative of their use in evaluating feedstock suitability for vermicomposting. Solvita stability tests did not correlate with carbon dioxide evolution tests nor ranking of stability by the same test, presumably due to in situ inhibition of decomposition and microbial respiration by ammonia which were reported by the Solvita CO2 test as having high stability values.
Collapse
Affiliation(s)
- Geoffrey B Hill
- University of British Columbia, Department of Geography, 1984 West Mall, Vancouver, Canada V6T 1Z2.
| | | | | |
Collapse
|
17
|
Hill GB, Baldwin SA, Vinnerås B. Composting toilets a misnomer: excessive ammonia from urine inhibits microbial activity yet is insufficient in sanitizing the end-product. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2013; 119:29-35. [PMID: 23435183 DOI: 10.1016/j.jenvman.2012.12.046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Revised: 10/21/2012] [Accepted: 12/28/2012] [Indexed: 06/01/2023]
Abstract
End-product from 16 public mixed latrine style composting toilets (CTs) at 12 sites between 50 and 2100 m.a.s.l. in Western North America was tested in order to evaluate the effect of composting variables (TS%, NH3-N, temperature, and material age) on compost quality and hygiene (VS%, Escherichia coli, [Formula: see text] -N, and pH). Principal component analysis indicated that TS%, temperature, and material age equally contributed to reduction in VS%. NH3-N had the greatest effect on [Formula: see text] -N, E. coli, and pH. Nitrification was significantly inhibited above 386 mg/kg NH3-N, but no such limit was found for E. coli, despite a significant (p = 0.016) but weak (r(2) = 0.11) negative relationship. It may be possible to amplify the sanitizing effect of ammonia and overcome pathogen resistance due to low temperatures and re-contamination (caused by poor design) with generous dosing of urea and ash. However, even sanitized, the fertilization effect of discharged material on the natural environment may not be desired or permitted in parks or protected areas where many CTs were found. To this end, operators of CTs need to evaluate their primary management objectives and ensure congruency with proven system capabilities.
Collapse
Affiliation(s)
- Geoffrey B Hill
- Department of Geography, University of British Columbia, 1984 West Mall, Vancouver, BC, Canada V6T 1Z2.
| | | | | |
Collapse
|