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Demonstrating removal credits for contaminants of emerging concern in recycled water through a reverse osmosis barrier-A predictive framework. WATER RESEARCH 2023; 244:120427. [PMID: 37567126 DOI: 10.1016/j.watres.2023.120427] [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: 02/09/2023] [Revised: 07/26/2023] [Accepted: 07/27/2023] [Indexed: 08/13/2023]
Abstract
The performance of individual reverse osmosis (RO) systems varies significantly with different contaminants of emerging concern (CECs). As such, log reduction values (LRVs) of the concentration of these chemicals cannot be arbitrarily credited in water treatment and water recycling. This study looks to present an approach to the management of chemical risks by providing a systematic validation of RO barrier performance with respect to LRV credits for various classes of CECs. In this work, a one-off sampling campaign across five treatment barriers (strainer filtration, ultrafiltration, RO, ion exchange, chlorination) of a full-scale water recycling plant was conducted, followed by a systematic sampling campaign for a period of six weeks across just the RO barrier. The CECs screening methodology used GC-MS for quantification of 948 trace organic chemicals along with specific 44 per- and polyfluoroalkyl substances (PFAS) screening using LC-MS/MS to demonstrate the removal credits of the RO barrier to a wide spectrum of CECs. The work was used to validate an LRV barrier credit framework so as to predict the performance of a polyamide RO membrane for removal of a range of chemical classes, under typical operational conditions. Conductivity was validated as an efficient surrogate for membrane integrity and RO performance, along with specified operational conditions associated with permeate flux and recovery rate. A bioassay method (photobacterium test) showed good potential to be used as a quick measure to indicate the general toxicity of a sample caused by chemical contamination, because of its high detection sensitivity and time and cost efficiency.
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Sub-ppm determination of perfluorinated carboxylic acids in solution by UV-vis high-performance liquid chromatography through solid phase extraction. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART A, TOXIC/HAZARDOUS SUBSTANCES & ENVIRONMENTAL ENGINEERING 2023; 58:605-616. [PMID: 37095699 DOI: 10.1080/10934529.2023.2204801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
This study investigated a novel and sensitive analytical method based on a simple heat-based derivatization using 3-bromoacetyl coumarin as the reagent and analysis with a HPLC-UV system or just a UV-vis spectrometer to allow the sub-ppm determination of PFCAs in water solution with the potential for utilization in simple laboratories and field laboratory scenarios. A Strata-X-AW cartridge was used for the solid phase extraction (SPE) procedure and higher than 98% recoveries were obtained. The derivatization condition showed that a high efficiency of peak separation was obtained with obviously different retention time among various PFCAs derivatives using HPLC-UV analysis. The derivatization stability and repeatability showed favorable results with stable derivatized analytes for ≤12 h and a relative standard deviation (RSD) of <2% for all repetitions. The limit of detection for the HPLC-UV analysis was between 0.1 ppm and 0.5 ppm. A satisfactory linearity response was found with R2 >0.998 for all individual PFCA compounds. The limit of detection for simple UV-Vis analysis was <0.0003 ppm to measure the presence of PFCAs. Contamination of standards with humic substances and measurement of industrial samples in a complex wastewater matrix showed no adverse effects on the accuracy of PFCA determination by using the developed methodology.
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A chemical credit framework to predict the removal performance of organic chemicals of concern from water through an ozonation process. WATER RESEARCH 2023; 232:119671. [PMID: 36736247 DOI: 10.1016/j.watres.2023.119671] [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: 10/11/2022] [Revised: 12/11/2022] [Accepted: 01/25/2023] [Indexed: 06/18/2023]
Abstract
Ozonation is an effective barrier for removing a wide spectrum of organic Chemicals of Concern (CoC) in a water treatment process. In this study, bench- and full-scale tests were conducted on a secondary treated effluent at the Eastern Treatment Plant (ETP) of Melbourne Water to probe the performance of ozonation in removing CoC in a wastewater discharge. From the secondary treated effluent as the feed to the ozone process, 58 organic chemicals were measured out of a possible 949 compounds by using the AIQS-DB analytical method. A chemical credit framework for the ozonation process has been established according to the bench-scale results. Chemical classifications based on the chemical structures (aromatics, aliphatic and halogenated aliphatic compounds) and reaction rate constants with O3 (KO3) and the ∙OH radical (K∙OH) and a combined O3/TOC ratio and O3 CT value as operating parameters were confirmed to be useful and important in determining whether a chemical would be removed by ozone. It is shown that an O3/TOC ratio of >0.404 was shown to be necessary to overcome the instantaneous ozone demand (IOD) to guarantee enough ozone to oxidise CoC. For CoC with KO3 >105M - 1s - 1 and K∙OH >109M - 1s - 1, an O3/TOC ratio of ≥0.461 or a measurable O3 CT of ≥0.063 mg min/L can achieve log reduction values (LRVs) of ≥1, these are chemicals with aromatic structures; For CoC with low KO3 and high KOH, a combined O3/TOC ratio and O3 CT value inclusive of a chemical structure classification is indicated as necessary criteria to evaluate the removal. UV254 and TOC were demonstrated to be good online surrogates of ozone barrier performance in the absence of continuous O3/TOC ratio and O3 CT value measurements. Full-scale operational results confirm the effective predictions of the chemical credit framework, which highlights the necessity and importance of monitoring both the O3/TOC ratio and O3 CT values to predict the removal efficiency of a given chemical with a known response to O3 or a known chemical structure.
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Physicochemical and rheological properties of commercial almond-based yoghurt alternatives to dairy and soy yoghurts. FUTURE FOODS 2022. [DOI: 10.1016/j.fufo.2022.100185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022] Open
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Interplay between interfacial behaviour, cell structure and shear enables biphasic lipid extraction from whole diatom cells (Navicula sp.). J Colloid Interface Sci 2021; 589:65-76. [PMID: 33450461 DOI: 10.1016/j.jcis.2020.12.056] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 11/25/2020] [Accepted: 12/17/2020] [Indexed: 10/22/2022]
Abstract
HYPOTHESIS Bacillariophyceae (i.e., diatoms) are an important class of algae with potential use in the production of proteins and lipids including long-chain ω-3 polyunsaturated fatty acids. Biphasic extraction of microalgae lipids using water-immiscible solvents such as hexane, can avoid the excessive energy required to distil solvents from water, but generally requires energy-intensive rupture of the cells. The unique cell structure and surface chemistry of diatoms compared to other microalgae species might allow biphasic lipid extraction without prior cell rupture. EXPERIMENTS The kinetics of biphasic lipid extraction from intact Navicula sp. cells was investigated during low-shear and high-shear mixing, and with prior or simultaneous application of ultrasound (20 kHz at 0.57 W/mL). Dynamic interfacial tension measurements and electron microscopic analysis were used to investigate lipid extraction in relation to interfacial behaviour and cell structure. RESULTS High yields (>80%) of intracellular lipids were extracted from intact cells over the course of hours upon low-shear contacting with hexane. The cells associated with and stabilised the hexane-water interface, allowing hexane to infiltrate pores in the frustule component of the cell walls and access the intracellular lipids. It was shown that mucilaginous extracellular polymeric substances (EPS) bound to the cell walls acted as a barrier to solvent penetration into the cells. This EPS could be removed by prior ultrasonication. Biphasic extraction was greatly accelerated by shear applied by rotor-stator mixing or ultrasound. High-shear could remove mucilaginous EPS from the cell surfaces to facilitate direct contact of the cell surface with hexane and produced smaller emulsion droplets with increased surface area. The combination of high-shear in the presence of hexane resulted in the in-situ rupture of the cells, which greatly accelerated lipid extraction and allowed high yields of neutral lipid (>95%) to be recovered from freshly harvested cells within less than 5 min. The study demonstrated the ability of shear to enable simultaneous cell rupture and lipid extraction from a diatom alga based on its cell structure and interfacial behaviour.
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Effect of Bulk Viscosity and Emulsion Droplet Size on the Separation Efficiency of Model Mineral Oil-in-Water (O/W) Emulsions under Ultrasonic Standing Wave Fields: A Theoretical and Experimental Investigation. Ind Eng Chem Res 2020. [DOI: 10.1021/acs.iecr.0c00616] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Wastewater treatment using filamentous algae - A review. BIORESOURCE TECHNOLOGY 2020; 298:122556. [PMID: 31843358 DOI: 10.1016/j.biortech.2019.122556] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 12/02/2019] [Accepted: 12/02/2019] [Indexed: 06/10/2023]
Abstract
Wastewater treatment using algae is a promising approach for efficient removal of contaminating nutrients and their conversion into useful products. Monocultures of filamentous algae provide easier harvesting compared to microalgae, and better control of biomass quality than polyculture systems such as algal turf scrubbers. In this review, recent research into wastewater treatment using freshwater filamentous algae is compiled and critically analysed. Focus is given to filamentous algae monocultures, with key relevant findings from microalgae and polyculture systems discussed and compared. The application of monocultures of filamentous algae is an emerging area of research. Gaps are identified in our understanding of key aspects important to large-scale system design, including criteria for species selection, influence of nutrient type and loading, inorganic carbon supply, algae-bacteria interactions, and parameters such as pond depth, mixing and harvesting regimes. This technology has much promise, however future research is needed to maximise productivity and wastewater treatment efficiency.
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Ozone combined with ceramic membranes for water treatment: Impact on HO radical formation and mitigation of bromate. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2020; 253:109655. [PMID: 31654925 DOI: 10.1016/j.jenvman.2019.109655] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2018] [Revised: 09/18/2019] [Accepted: 09/28/2019] [Indexed: 06/10/2023]
Abstract
The beneficial effect of combining ozone with ceramic membrane filtration (CMF) to enhance membrane flux performances during water treatment (e.g., wastewater and drinking water) could be related to the formation of hydroxyl (HO) radicals from the interaction of ozone with ceramic membrane. To explore this effect, para-chlorobenzoic acid was used to probe HO radical activity during a combined ozone/CMF process using a 0.1 μm pore size membrane supplied by Metawater, Japan. Tests were then extended to explore the impact on bromate formation downstream CMF, a well-known undesirable by-product from ozone use in water treatment. Ozone reduction by the membrane and its module appeared to be more associated with physical degassing, but a noticeable formation of HO radicals was observed during the interaction of ozone with the ceramic membrane. CMF treatment of ozonated potable water containing bromide showed a reduced bromate formation of 50% when the water was recirculated to the filtration module containing the ceramic membrane, compared to the experiment performed with an empty module. Single pass experiments showed bromate mitigation of around 10%. The mitigation of bromate formation was attributed to reduced overall ozone exposure by deagassing effect, but also potentially from suppression of the oxidation of Br- and HOBr/BrO- to BrO3- due to the catalytic degradation of ozone via a HO radical pathway.
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A critical control point approach to the removal of chemicals of concern from water for reuse. WATER RESEARCH 2019; 160:39-51. [PMID: 31129380 DOI: 10.1016/j.watres.2019.05.035] [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: 09/26/2018] [Revised: 05/08/2019] [Accepted: 05/11/2019] [Indexed: 06/09/2023]
Abstract
The reuse of water in a range of potable and non-potable applications is an important factor in the augmentation of water supply and in improving water security and productivity worldwide. A key hindrance to the reuse of water is the cost of compliance testing and process validation associated with ensuring that pathogen and chemicals in the feedwater are removed to a level that ensures no acute or chronic health and/or environmental effects. The critical control point (CCP) approach is well established and widely adopted by water utilities to provide an operational and risk management framework for the removal of pathogens in the treatment system. The application of a CCP approach to barriers in a treatment system for the removal of chemicals is presented. The application exemplar is to a small community wastewater treatment system that aims to produce potable quality water from a secondary treated wastewater effluent, however, the concepts presented are generic. The example used seven treatment barriers, five of which were designed and operated as CCP barriers for pathogens. The work demonstrates a method and risk management framework by which three of the seven barriers could also include a CCP approach for the removal of chemicals. Analogous to a CCP approach for pathogens, the potential is to reduce the use of chemical analysis as a routine determinant of performance criteria. The operational deployment of a CCP approach for chemicals was augmented with the development of a decision tree encompassing the classification of chemicals and the total removal credits across the treatment train in terms of the mechanistic removal of chemicals for each barrier. Validation of the approach is shown for an activated sludge, ozone and reverse osmosis barrier.
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Synergistic Influence of pH and Temperature on Rheological Behavior of Adhesive Emulsions Stabilized with Micelle Dispersion of an Anionic Surfactant. J SURFACTANTS DETERG 2018. [DOI: 10.1002/jsde.12220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Wastewater recycling in Antarctica: Performance assessment of an advanced water treatment plant in removing trace organic chemicals. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2018; 224:122-129. [PMID: 30036806 DOI: 10.1016/j.jenvman.2018.07.020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 07/01/2018] [Accepted: 07/06/2018] [Indexed: 06/08/2023]
Abstract
The Australian Antarctic Division (AAD) operates Australia's Davis Station in the Antarctic. In 2005, Davis Station's wastewater treatment plant failed and since then untreated, macerated effluent has been discharged to the ocean. The objectives of this study were to determine whether an advanced water treatment plant (AWTP) commissioned by the AAD and featuring a multi-barrier process involving ozonation, ceramic microfiltration, biologically activated carbon filtration, reverse osmosis, ultraviolet disinfection and chlorination was capable of producing potable water and a non-toxic brine concentrate that can be discharged with minimal environmental impact. The AWTP was tested using water from a municipal wastewater treatment plant in Tasmania, Australia. We used spot water and passive sampling combined with two multi-residue chromatographic-mass spectrometric methods and a range of recombinant receptor-reporter gene bioassays to screen trace organic chemicals (TrOCs), toxicity and receptor activity in the Feed water, in the environmental discharge (reject water), and product water from the AWTP for six months during 2014-15, and then again for three months in 2016. Across the two surveys we unambiguously detected 109 different TrOCs in the feed water, 39 chemicals in the reject water, and 34 chemicals in the product water. Sample toxicity and receptor activity in the feed water samples was almost totally removed in both testing periods, confirming that the vast majority of the receptor active TrOCs were removed by the treatment process. All the NDMA entering the AWTP in the feed and/or produced in the plant (typically < 50 ng/L), was retained into the reject water with no NDMA observed in the product water. In conclusion, the AWTP was working to design, and releases of TrOCs at the concentrations observed in this study would be unlikely cause adverse effects on populations of aquatic organisms in the receiving environment or users of the potable product water.
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Conversion and recovery of saponifiable lipids from microalgae using a nonpolar solvent via lipase-assisted extraction. BIORESOURCE TECHNOLOGY 2018; 260:338-347. [PMID: 29649726 DOI: 10.1016/j.biortech.2018.03.129] [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: 02/09/2018] [Revised: 03/26/2018] [Accepted: 03/29/2018] [Indexed: 05/13/2023]
Abstract
A single-step method for transesterifying and recovering lipids in concentrated slurries (ca 20% w/w solids) of ruptured microalgae is presented. A soluble Rhizomucor miehei lipase (RML) was used to directly transesterify the lipids in the marine microalgae Nannochloropsis salina. This allowed both triglycerides (TAG) and polar saponifiable lipids to be recovered as fatty acid methyl esters (FAME) using a nonpolar solvent (hexane). Up to 90 wt% of the total saponifiable lipids (SL) were converted to FAME within 24 h, approximately 75% of which was recovered in the hexane by centrifugation. Two pathways for the conversion and recovery of polar lipids were identified. The water in the slurry buffered against potential lipase inhibition by methanol, but necessitated a high methanol dose for maximal FAME conversion. Nonetheless the method enables the recovery of polar lipids as FAME while avoiding the need for both drying of the biomass and a downstream transesterification step.
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Compartmentalization of extracellular polymeric substances (EPS) solubilization and cake microstructure in relation to wastewater sludge dewatering behavior assisted by horizontal electric field: Effect of operating conditions. WATER RESEARCH 2018; 130:363-375. [PMID: 29253807 DOI: 10.1016/j.watres.2017.11.060] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Revised: 11/23/2017] [Accepted: 11/28/2017] [Indexed: 06/07/2023]
Abstract
Sludge treatment and disposal have become important environmental issues in China. Mechanical dewatering is widely used to reduce the amount of sludge to be disposed and relieve the rapid growth pressure of waste sludge. In comparison to traditional sludge dewatering processes, pressure electro-osmotic dewatering has many advantages on sludge dewatering efficiency, low conditioner dosage and concentrated cake are both beneficial to further recycling of waste sludge. In general, complex electrochemical effects (eg. electrochemical oxidation, ohmic heating and pH gradient effect) are accompanied by the pressure electro-osmotic dewatering process. These electrochemical effects will inevitably cause solubilization and/or degradation of key constituents of wastewater sludge - extracellular polymeric substances (EPS). In this study, the effects of voltage, pH and ionic strength on sludge electro-osmotic dewatering performance and electrochemical effects were investigated. The solubilization and degradation of EPS were analyzed by examining the variation of dissolved organic matter (DOM) in the filtrate, and the relationships between microstructural properties of sludge cake and DOM and electro-osmosis dewatering performance in electro-dewatering process was examined. It was found that electro-dewatering properties were improved by raising the operating voltage or decreasing the pH value, while dewatering rate initially increased at low ionic strength it decreases with increased ionic strength. In addition, the porous structure of cathodic cake was more plentiful than that at the anode. At the cathode, the EPS dissolution was mainly related to alkalization, while the oxidation and acidification were responsible for release of EPS at the anode. Meanwhile, electrophoresis effect was able to promote migration of EPS toward the anode. The average electro-osmotic dewatering rate at the anode (R2.>0.79, p < 0.02) and at the cathode (R2.>0.87, p < 0.03) strongly correlated with the volume of pore of sludge cake. There was no correlation between the total content of anodic DOM (R2<0.31, p>0.08) and electro-osmotic dewatering rate at the anode, however, the content of cathodic DOM (R2 > 0.62, p < 0.09) negatively correlated with average electro-osmosis dewatering rate of cathode. Since cathode is the main water-permeable side in sludge electro-dewatering, and the sticky biopolymers (proteins and humic subtances) could not be converted into small molecules, higher EPS release was associated with worse sludge filterability. As for the anode, the biopolymers were degraded into small molecules due to electrochemical oxidation, which greatly reduced the impact of DOM on dewatering effect. Therefore, the operating conditions (voltage, pH and ionic strength) caused changes in electrochemical effects, which played a crucial role in compartmentalization of sludge EPS dissolution and consequently sludge electro-dewatering behavior.
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Abstract
3D-printable self-healing oxime gels have been reinforced by cryogelation, making these gels mechanically tuneable, macroporous, and doubly dynamic.
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Predicting Transmembrane Pressure Rise from Biofouling Layer Compressibility and Permeability. Chem Eng Technol 2017. [DOI: 10.1002/ceat.201700117] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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The influence of protruding filamentous bacteria on floc stability and solid-liquid separation in the activated sludge process. WATER RESEARCH 2017; 123:578-585. [PMID: 28704773 DOI: 10.1016/j.watres.2017.06.063] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 06/21/2017] [Accepted: 06/22/2017] [Indexed: 06/07/2023]
Abstract
Filamentous bacteria can impact on the physical properties of flocs in the activated sludge process assisting solid-liquid separation or inducing problems when bacteria are overabundant. While filamentous bacteria within the flocs are understood to increase floc tensile strength, the relationship between protruding external filaments, dewatering characteristics and floc stability is unclear. Here, a quantitative methodology was applied to determine the abundance of filamentous bacteria in activated sludge samples from four wastewater treatment plants. An automated image analysis procedure was applied to identify filaments and flocs and calculate the length of the protruding filamentous bacteria (PFB) relative to the floc size. The correlation between PFB and floc behavior was then assessed. Increased filament abundance was found to increase interphase drag on the settling flocs, as quantified by the hindered settling function. Additionally, increased filament abundance was correlated with a lower gel point concentration leading to poorer sludge compactability. The floc strength factor, defined as the relative change in floc size upon shearing, correlated positively with filament abundance. This influence of external protruding filamentous bacteria on floc stability is consistent with the filamentous backbone theory, where filamentous bacteria within flocs increase floc resistance to shear-induced breakup. A qualitative correlation was also observed between protruding and internal filamentous structure. This study confirms that filamentous bacteria are necessary to enhance floc stability but if excessively abundant will adversely affect solid-liquid separation. The tools developed here will allow quantitative analysis of filament abundance, which is an improvement on current qualitative methods and the improved method could be used to assist and optimize the operation of waste water treatment plants.
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Centrifugal recovery of solvent after biphasic wet extraction of lipids from a concentrated slurry of Nannochloropsis sp. biomass. ALGAL RES 2017. [DOI: 10.1016/j.algal.2017.04.016] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Ammonium removal from high-strength aqueous solutions by Australian zeolite. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART A, TOXIC/HAZARDOUS SUBSTANCES & ENVIRONMENTAL ENGINEERING 2016; 51:614-625. [PMID: 27050255 DOI: 10.1080/10934529.2016.1159861] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Removal of ammonium nitrogen (NH4(+)-N) particularly from sources which are highly rich in nitrogen is important for addressing environmental pollution. Zeolites, aluminosilicate minerals, are commonly used as commercial adsorbents and ion-exchange medium in number of commercial applications due to its high adsorption capacity of ammonium (NH4(+)). However, detailed investigations on NH4(+) adsorption and ion exchange capacities of Australian natural zeolites are rare, particularly under higher NH4(+) concentrations in the medium. Therefore, this study was conducted to determine NH4(+) adsorption characteristics of Australian natural zeolites at high NH4(+) concentrations with and without other chemical compounds in an aqueous solution. Results showed that initial NH4(+) concentration, temperature, reaction time, and pH of the solution had significant effects on NH4(+) adsorption capacity of zeolite. Increased retention time and temperature generally had a positive impact on adsorption. Freundlich model fitted well with adsorption process of Australian natural zeolites; however, Langmuir model had best fitted for the adsorption process of sodium (Na(+)) treated zeolites. NaCl treatment increased the NH4(+) adsorption capacity of Australian zeolites by 25% at 1000 mg-N, NH4(+) solution. The maximum adsorption capacity of both natural Australian zeolites and Na(+) treated zeolites were estimated as 9.48 and 11.83 mg-N/g, respectively, which is lower than many zeolites from other sources. Compared to the NH4(+) only medium, presence of other competitive ions and acetic acid in the medium (resembling composition in digested swine manure slurries) reduced NH4(+) removal of natural and Na(+) treated zeolites by 44% and 57%, respectively. This suggests detailed investigations are required to determine practically achievable NH4(+) -N removal potential of zeolites for applications in complex mediums such as animal manure slurries.
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Abstract
The use of phages to control and reduce numbers of unwanted bacteria can be traced back to the early 1900s, when phages were explored as a tool to treat infections before the wide scale use of antibiotics. Recently, phage therapy has received renewed interest as a method to treat multiresistant bacteria. Phages are also widely used in the food industry to prevent the growth of certain bacteria in foods, and are currently being explored as a tool for use in bioremediation and wastewater treatment. Despite the large body of biological research on phages, relatively little attention has been given to computational modeling of the population dynamics of phage and bacterial interactions. The earliest model was described by Campbell in the 1960s. Subsequent modifications to this model include partial or complete resistance, multiple phage binding sites, and spatial heterogeneity. This review provides a general introduction to modeling of the population dynamics of bacteria and phage. The review introduces the basic model and relevant concepts and evaluates more complex variations of the basic model published to date, including a model of disease epidemics caused by infectious bacteria. Finally, the shortcomings and potential ways to improve the models are discussed.
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A non-linear viscoelastic model for sediments flocculated in the presence of seawater salts. Colloids Surf A Physicochem Eng Asp 2015. [DOI: 10.1016/j.colsurfa.2015.06.036] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Quantification of wastewater sludge dewatering. WATER RESEARCH 2015; 82:2-13. [PMID: 26003332 DOI: 10.1016/j.watres.2015.04.045] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Revised: 04/09/2015] [Accepted: 04/13/2015] [Indexed: 06/04/2023]
Abstract
Quantification and comparison of the dewatering characteristics of fifteen sewage sludges from a range of digestion scenarios are described. The method proposed uses laboratory dewatering measurements and integrity analysis of the extracted material properties. These properties were used as inputs into a model of filtration, the output of which provides the dewatering comparison. This method is shown to be necessary for quantification and comparison of dewaterability as the permeability and compressibility of the sludges varies by up to ten orders of magnitude in the range of solids concentration of interest to industry. This causes a high sensitivity of the dewaterability comparison to the starting concentration of laboratory tests, thus simple dewaterability comparison based on parameters such as the specific resistance to filtration is difficult. The new approach is demonstrated to be robust relative to traditional methods such as specific resistance to filtration analysis and has an in-built integrity check. Comparison of the quantified dewaterability of the fifteen sludges to the relative volatile solids content showed a very strong correlation in the volatile solids range from 40 to 80%. The data indicate that the volatile solids parameter is a strong indicator of the dewatering behaviour of sewage sludges.
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Designing thickeners by matching hindered settling and gelled suspension zones in the presence of aggregate densification. Chem Eng Sci 2015. [DOI: 10.1016/j.ces.2015.05.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Energy evaluation of algal cell disruption by high pressure homogenisation. BIORESOURCE TECHNOLOGY 2015; 184:280-285. [PMID: 25435068 DOI: 10.1016/j.biortech.2014.11.049] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2014] [Revised: 11/10/2014] [Accepted: 11/11/2014] [Indexed: 06/04/2023]
Abstract
The energy consumption of high pressure homogenisation (HPH) was analysed to determine the feasibility of rupturing algal cells for biodiesel production. Experimentally, the processing capacity (i.e. flow rate), power draw and cell disruption efficiency of HPH were independent of feed concentration (for Nannochloropsis sp. up to 25%w/w solids). Depending on the homogenisation pressure (60-150 MPa), the solids concentration (0.25-25%w/w), and triacylglyceride (TAG) content of the harvested algal biomass (10-30%), the energy consumed by HPH represented between 6% and 110-times the energy density of the resulting biodiesel. Provided the right species (weak cell wall and high TAG content) is selected and the biomass is processed at a sufficiently high solids concentration, HPH can consume a small fraction of the energy content of the biodiesel produced. This study demonstrates the feasibility of process-scale algal cell disruption by HPH based on its energy requirement.
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The effects of acidic and thermal pretreatment on the mechanical rupture of two industrially relevant microalgae: Chlorella sp. and Navicula sp. ALGAL RES 2015. [DOI: 10.1016/j.algal.2014.11.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Aggregate densification in the thickening of flocculated suspensions in an un-networked bed. Chem Eng Sci 2015. [DOI: 10.1016/j.ces.2014.10.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Lipid profile remodeling in response to nitrogen deprivation in the microalgae Chlorella sp. (Trebouxiophyceae) and Nannochloropsis sp. (Eustigmatophyceae). PLoS One 2014; 9:e103389. [PMID: 25171084 PMCID: PMC4149361 DOI: 10.1371/journal.pone.0103389] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2014] [Accepted: 06/29/2014] [Indexed: 12/29/2022] Open
Abstract
Many species of microalgae produce greatly enhanced amounts of triacylglycerides (TAGs), the key product for biodiesel production, in response to specific environmental stresses. Improvement of TAG production by microalgae through optimization of growth regimes is of great interest. This relies on understanding microalgal lipid metabolism in relation to stress response in particular the deprivation of nutrients that can induce enhanced TAG synthesis. In this study, a detailed investigation of changes in lipid composition in Chlorella sp. and Nannochloropsis sp. in response to nitrogen deprivation (N-deprivation) was performed to provide novel mechanistic insights into the lipidome during stress. As expected, an increase in TAGs and an overall decrease in polar lipids were observed. However, while most membrane lipid classes (phosphoglycerolipids and glycolipids) were found to decrease, the non-nitrogen containing phosphatidylglycerol levels increased considerably in both algae from initially low levels. Of particular significance, it was observed that the acyl composition of TAGs in Nannochloropsis sp. remain relatively constant, whereas Chlorella sp. showed greater variability following N-deprivation. In both algae the overall fatty acid profiles of the polar lipid classes were largely unaffected by N-deprivation, suggesting a specific FA profile for each compartment is maintained to enable continued function despite considerable reductions in the amount of these lipids. The changes observed in the overall fatty acid profile were due primarily to the decrease in proportion of polar lipids to TAGs. This study provides the most detailed lipidomic information on two different microalgae with utility in biodiesel production and nutraceutical industries and proposes the mechanisms for this rearrangement. This research also highlights the usefulness of the latest MS-based approaches for microalgae lipid research.
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A mechanistic study of algal cell disruption and its effect on lipid recovery by solvent extraction. ALGAL RES 2014. [DOI: 10.1016/j.algal.2014.07.001] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Low solvent, low temperature method for extracting biodiesel lipids from concentrated microalgal biomass. BIORESOURCE TECHNOLOGY 2013; 148:615-619. [PMID: 24080444 DOI: 10.1016/j.biortech.2013.09.022] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 09/02/2013] [Accepted: 09/03/2013] [Indexed: 06/02/2023]
Abstract
An industrially relevant method for disrupting microalgal cells and preferentially extracting neutral lipids for large-scale biodiesel production was demonstrated on pastes (20-25% solids) of Nannochloropsis sp. The highly resistant Nannochloropsis sp. cells. were disrupted by incubation for 15 h at 37°C followed by high pressure homogenization at 1200 ± 100 bar. Lipid extraction was performed by twice contacting concentrated algal paste with minimal hexane (solvent:biomass ratios (w/w) of <2:1 and <1.3:1) in a stirred vessel at 35°C. Cell disruption prior to extraction increased lipid recovery 100-fold, with yields of 30-50% w/w obtained in the first hexane contact, and a further 6.5-20% in the second contact. The hexane preferentially extracted neutral lipids over glyco- and phospholipids, with up to 86% w/w of the neutral lipids recovered. The process was effective on wet concentrated paste, required minimal solvent and moderate temperature, and did not require difficult to recover polar solvents.
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Pathogen reduction requirements for direct potable reuse in Antarctica: evaluating human health risks in small communities. THE SCIENCE OF THE TOTAL ENVIRONMENT 2013; 461-462:723-733. [PMID: 23770553 DOI: 10.1016/j.scitotenv.2013.05.059] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Revised: 05/20/2013] [Accepted: 05/20/2013] [Indexed: 06/02/2023]
Abstract
Small, remote communities often have limited access to energy and water. Direct potable reuse of treated wastewater has recently gained attention as a potential solution for water-stressed regions, but requires further evaluation specific to small communities. The required pathogen reduction needed for safe implementation of direct potable reuse of treated sewage is an important consideration but these are typically quantified for larger communities and cities. A quantitative microbial risk assessment (QMRA) was conducted, using norovirus, giardia and Campylobacter as reference pathogens, to determine the level of treatment required to meet the tolerable annual disease burden of 10(-6) DALYs per person per year, using Davis Station in Antarctica as an example of a small remote community. Two scenarios were compared: published municipal sewage pathogen loads and estimated pathogen loads during a gastroenteritis outbreak. For the municipal sewage scenario, estimated required log10 reductions were 6.9, 8.0 and 7.4 for norovirus, giardia and Campylobacter respectively, while for the outbreak scenario the values were 12.1, 10.4 and 12.3 (95th percentiles). Pathogen concentrations are higher under outbreak conditions as a function of the relatively greater degree of contact between community members in a small population, compared with interactions in a large city, resulting in a higher proportion of the population being at risk of infection and illness. While the estimates of outbreak conditions may overestimate sewage concentration to some degree, the results suggest that additional treatment barriers would be required to achieve regulatory compliance for safe drinking water in small communities.
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Quantitative evaluation of the ease of rupture of industrially promising microalgae by high pressure homogenization. BIORESOURCE TECHNOLOGY 2013; 140:165-171. [PMID: 23688668 DOI: 10.1016/j.biortech.2013.04.074] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Revised: 04/17/2013] [Accepted: 04/19/2013] [Indexed: 06/02/2023]
Abstract
The susceptibility to rupture of the microalgae Nannochloropsis sp., Chlorella sp. and Tetraselmis suecica by high pressure homogenization was compared quantitatively to the yeast Saccharomyces cerevisiae. Methods for quantifying cell rupture were investigated including cell counting, turbidity, metabolite release and particle sizing. Cell counting was the only reliable method for quantitative comparisons of all microalgae, with turbidity complicated by agglomeration of cell debris for T. suecica, and measurement of metabolite release affected by degradation occurring for all microalgae after significant rupture. The rupture of all microalgae followed exponential decay as a function of number of passes. The pressure required to achieve rupture of 50% of the cells per pass was determined to be 170, 1070, 1380, and ca. 2000 bar for Tetraselmis sp., Chlorella sp., S. cerevisiae, and Nannochloropsis sp., respectively. These results extend the criteria for selecting microalgae for industrial applications beyond consideration of growth and compositional attributes.
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Dry stacking of wastewater treatment sludges. WATER RESEARCH 2013; 47:3534-3542. [PMID: 23642401 DOI: 10.1016/j.watres.2013.04.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Revised: 03/27/2013] [Accepted: 04/01/2013] [Indexed: 06/02/2023]
Abstract
Drying pans are used during wastewater treatment (WWT) to store, stabilise and dry residual solids. The pans are filled with sludge that dries via exposure to sunshine and wind. We propose that drying pans be operated based on dry stacking principles, a technique with proven success in the mineral processing industry. The implementation of the dry stacking technique requires very little in the way of additional engineering beyond a conventional drying pan. By applying the sludge in thin layers, the sludge naturally forms its own stack with an angle that is dependent on the consistency of the material. The benefits of dry stacking are that the slope allows instantaneous run-off of rainfall and supernatant, allowing operation throughout the year rather than seasonally. The layering approach also maximises the evaporation achieved in the available deposition area compared to filling the pans sequentially. A series of laboratory tests were carried out on samples from Melbourne Water's Western Treatment Plant in Werribee, Australia, to provide validation of the dry stacking concept for WWT sludges. Rheological tests showed that samples had appropriate flow properties to form stacks. Drying and re-wetting tests on the samples indicated that a sloped, partially dry sludge sheds rainfall, depending on the slope, cake dryness and amount of rainfall. Local rainfall data was used to estimate a potential increase in pan throughput of 65%-140% due to dry stacking. The greatest improvements were predicted to occur during wetter years. In combination, the results indicated that dry stacking has the potential to dramatically improve the performance of WWT sludge drying pans.
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Pseudo two-dimensional modeling of sediment build-up in centrifuges: A compartment approach using compressional rheology. AIChE J 2013. [DOI: 10.1002/aic.14115] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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A quantitative analysis of microalgal lipids for optimization of biodiesel and omega-3 production. Biotechnol Bioeng 2013; 110:2096-104. [DOI: 10.1002/bit.24844] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Revised: 12/11/2012] [Accepted: 01/07/2013] [Indexed: 11/08/2022]
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Critical analysis of quantitative indicators of cell disruption applied to Saccharomyces cerevisiae processed with an industrial high pressure homogenizer. Biochem Eng J 2013. [DOI: 10.1016/j.bej.2012.10.008] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Effects of solvency and interfacial nanobubbles on surface forces and bubble attachment at solid surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:2484-2491. [PMID: 21294556 DOI: 10.1021/la1042074] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The forces between a carbon sphere and highly ordered pyrolytic graphite (HOPG) surface were measured in ethanol aqueous solutions. A long-range attractive interaction was observed in ethanol aqueous solutions with less than 60% ethanol on a volume basis. The magnitude and the range of the attractive interaction decreased with an increase in ethanol concentration in solution. An air bubble was found to attach to the HOPG surface in solutions with an ethanol concentration less than 20 vol %. The presence of nanobubbles at the HOPG surface, made possible through a surface washing process and confirmed through in situ imaging, extended the range of both the long-range attraction and the bubble attachment regime to ethanol concentrations 60-80 vol %. The shear yield stress of suspensions of carbon black in ethanol-aqueous solutions was used as an indicator of the presence of a net attractive interaction between particles. The yield stress was observed to increase rapidly for ethanol concentrations less than 60 vol %. Contact angle analysis for ethanol-aqueous solutions in air showed that an angle of greater than 40° was required to induce a long-range attraction. Modeling indicated that the range and form of the interaction was consistent with a capillary cavitation force. The data clearly shows that surface nanobubbles are not critical to the development of a long-range attractive force, bubble pickup on surfaces, or enhanced suspension rheology, but that their presence greatly aids these processes.
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Semi-empirical full cycle optimisation of fill, squeeze and blow plate and frame pressure filters. Chem Eng Sci 2010. [DOI: 10.1016/j.ces.2010.01.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Assessing dewatering performance of drinking water treatment sludges. WATER RESEARCH 2010; 44:1542-1552. [PMID: 19944445 DOI: 10.1016/j.watres.2009.10.036] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2009] [Revised: 10/11/2009] [Accepted: 10/29/2009] [Indexed: 05/28/2023]
Abstract
A comparison of the dewaterability of a range of water treatment plant sludges has been completed through computation of dewatering performance indicators for a diaphragm filter press. Real parameter data, obtained from the characterisation of alum and ferric sludges, generated under precisely controlled conditions, was used for input to a phenomenological model. Comparisons of dewaterability based on throughput curves largely agree with previous analysis of the underlying parameter data. The difference in approach provides a quantification of benefit. Greater throughputs and output concentrations are predicted at the lowest coagulant doses and at pH approximately 6. Typical industrial cloth resistances consistently reduce throughput by a factor of 3-7, but the assessment of relative benefit is shown to be insensitive to this parameter. Quantitative agreement of the predictions with observed performance can be attained. Finally, the twin effects of solids loading and dewaterability are assessed together, showing that each has a significant influence on the required filter surface area. This quantification shows that high coagulant doses adversely affect both of these aspects, leading to filter area requirements larger than might otherwise be expected.
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The influence of ionic strength and osmotic pressure on the dewatering behaviour of sewage sludge. Chem Eng Sci 2009. [DOI: 10.1016/j.ces.2009.01.043] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Fundamental dewatering properties of wastewater treatment sludges from filtration and sedimentation testing. Chem Eng Sci 2008. [DOI: 10.1016/j.ces.2008.07.016] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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