@article {27775, title = {Characterization and modelling of distinct soluble microbial products in SBRs treating municipal wastewater with special emphasis on temperature effect}, journal = {Science of the Total Environment}, year = {10030}, author = {C. Tao and W. Parker and P. Berube} } @article {27300, title = {Impact of AnMBR operating conditions on anaerobic digestion of waste activated sludge}, journal = {Water Environment Research }, year = {2020}, abstract = {

The impact of solids retention time (SRT) and hydraulic retention time (HRT) on anaerobic digestion of thickened waste activated sludge (TWAS) in a pilot-scale anaerobic membrane bioreactor (AnMBR) was compared with that achieved in conventional anaerobic digestions (CD). The AnMBR was able to successfully digest municipal TWAS at HRTs ranging from 7 to 15\ days and SRTs ranging from 15 to 30\ days. Increasing SRT in the AnMBR resulted in a significant improvement in COD and VS removal efficiency when compared against CD operating at the same HRT. The VS and COD destructions (35\%{\textendash}50\%) observed in the AnMBR were similar to those observed in CD operating at the same SRT but longer HRTs. Operation at elevated ratios of SRT/HRT resulted in the production of a thickened biosolid (2\%{\textendash}3\% TS). Specific methane production values for AnMBR operating at HRT-SRT ratios of 15{\textendash}30, 7{\textendash}30, and 7{\textendash}15 were 0.19, 0.19, and 0.14\ m3\ CH4/kg of COD fed, respectively, showing a 25\% increase in methane production with SRT. A model based upon describing hydrolysis of biodegradable solids using first-order kinetics was able to describe VS destruction as a function of SRT.

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Practitioner points

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}, author = {Wayne Parker and Martha Dagnew} } @article {27301, title = {Treatment of municipal wastewater in AnMBRs with powdered activated carbon addition under psychrophilic temperatures}, journal = {Water Environment Research }, volume = {93}, year = {2020}, abstract = {

The performance of anaerobic membrane bioreactors (AnMBRs) at psychrophilic temperatures commonly observed in temperate climates (10{\textendash}24{\textdegree}C) was assessed. A unique aspect of the research was operation at controlled SRT with regular membrane cleaning. COD removal and permeate VFA concentrations were similar at 15 and 24{\textdegree}C and deteriorated at 10{\textdegree}C. As temperature decreased, the COD mass flow to methane decreased and COD mass flows in the permeate and waste sludge increased. At 24{\textdegree}C, rapid membrane TMP increases were not observed while at 15 and 10{\textdegree}C rapid increases occurred at 11.7\ {\textpm}\ 0.46 and 7.6\ {\textpm}\ 0.45\ days, respectively, indicating a greater fouling propensity of the mixed liquor at lower temperatures. When the temperature was reduced from 15{\textdegree}C to 10{\textdegree}C in a transient test, CH4\ production was reduced and VFA concentrations increased. A 2{\textendash}3 SRT lag in the responses suggested that the delayed response was due to long-term changes in microbial population. The permeate VFA content in a PAC-dosed reactor was lower than that without PAC dosing, and PAC addition increased the time to rapid TMP development to 11.3\ {\textpm}\ 0.46\ days from 7.4\ {\textpm}\ 0.49\ days. The primary benefit of PAC addition at low temperatures is enhanced membrane performance.

Practitioner points

}, author = {Wayne Parker and Linda Li} } @article {27302, title = {Assessment of the use of mainstream iron addition for phosphorous control on H2S content of biogas from anaerobic digestion of sludges}, journal = {Water Environment Research }, volume = {92}, year = {2019}, abstract = {

A material flux analysis on sulfur (S), phosphorus (P), aluminum (Al), and iron (Fe) was conducted for two WWTPs (Galt and Kitchener) to evaluate the potential of coagulants that are employed for phosphorus control to reduce hydrogen sulfide (H2S) emissions in the biogas from anaerobic digestion. It was found that while the Galt WWTP receives higher concentrations of S in the raw wastewater than the Kitchener WWTP, this had only a modest impact on the speciation of S entering anaerobic digestion. At both plants, only 2\%{\textendash}4\% of influent S entered the digesters. The presence of Fe in the sludge stream was found to cause S, that is released by volatile solid destruction and sulfate reduction, to become particulate-bound. A dosage of 1.1\ mg/L of Fe into the raw wastewater (11\% of the Fe dosed for P control) was sufficient for sulfide (S2-) control. Transitioning the Galt WWTP from Al to Fe dosing for P control had no significant impact on effluent P concentrations and resulted in a substantial reduction in the biogas H2S concentration. An additional secondary benefit was an increase in the solid content of the dewatered cake.

Practitioner points

}, author = {Wayne Parker and Dominika Celmer-Repin and Jose Bicudo and Pam Law} } @article {27284, title = {Evaluation of Dechlorinating Chemicals for Spent Membrane Cleaning Solutions}, journal = {Water Environment Research }, volume = {88}, year = {2016}, abstract = {The use of dechlorinating chemicals for removal of chlorine from spent membrane cleaning solutions was investigated. Addition of calcium thiosulfate resulted in a decrease in pH at low dosages of calcium thiosulfate, but when higher dosages were used, the pH was not affected. Other dechlorinating agents (sodium bisulfite, sodium sulfite, and ascorbic acid) generated smaller pH declines than calcium thiosulfate. The declines in pH were observed after the dechlorination reaction was effectively complete and pH did not appear to influence the rate of dechlorination. The rate of dechlorination in spent cleaning solution was slower than that observed in clean water. Dechlorination with calcium thiosulfate resulted in the lowest half-life and reaction time. At lower doses (less than 565 mg/L), it was not possible to discriminate between the different dechlorinating agents. The times required for dechlorination were more sensitive to increases in dechlorination chemical dose at lower doses.}, author = {Wayne Parker and Jiyun Ko and Jun Liu} } @article {27286, title = {Influence of SRT and HRT on Bioprocess Performance in Anaerobic Membrane Bioreactors Treating Municipal Wastewater}, journal = {Water Environment Research }, volume = {88}, year = {2016}, abstract = {This study investigated the impact of Solid Retention Time (SRT) (40 to 100 days) and Hydraulic Retention Time (HRT) (2.5 to 8.5 hours) on the treatment of municipal wastewater in pilot and bench scale AnMBRs. The results revealed good permeate quality with respect to concentrations of COD (\<40 mg/L) and BOD5\ (\<10 mg/L) was achieved under all conditions. Over the range of values tested SRT and HRTdid not significantly influence COD and BOD5\ removal efficiencies. Extended SRTs resulted in reduced sludge production and enhanced methane production. Oversaturation of dissolved methane in permeate appears to have been responsible for a consistent lack of COD mass balance closure in all tests. After calibration of biokinetic coefficients, PetWin 4 (EnviroSim Canada) was found to effectively simulate the concentrations of particulate COD, readily biodegradable COD and acetic acid over a range of SRTs and HRTs. The calibrated saturation coefficients for hydrolysis and aceticlastic methanogenesis processes were comparable to those reported in literature. The saturation coefficient of fermentation was significantly lower than those reported in literature. The simulated methane mass flows were consistently higher than the measured values which was consistent with the lack of COD mass balance closure and was attributed to reduction of sulfate and oversaturation of the permeate with respect to Henry{\textquoteright}s Law.}, author = {Wayne Parker and Qirong Dong and Martha Dagnew} } @article {27305, title = {Effect of pretreatment using ultrasound and hydrogen peroxide on digestion of waste activated sludge in an anaerobic membrane bioreactor}, journal = {Environmental Progress and Sustainable Energy }, volume = {34}, year = {2015}, abstract = {This study investigated combining pretreatment of waste activated sludge with anaerobic digestion in a submerged anaerobic membrane bioreactor. Preliminary tests revealed that a hydrogen peroxide and ultrasound pretreatment resulted in a chemical oxygen demand solubilization of 40\% when a dose of 50 gH2O2/kgTS and sonication for 60 min were employed. Raw and pretreated waste activated sludge were fed to an anaerobic membrane bioreactor to determine if this increase in solubilization affected the biodegradability of the sludge. It was observed that pretreatment increased the extent to which the sludge was digested and hence it was concluded that the combined action of ultrasound and peroxide increased the biodegradable fraction of the sludge, while reducing the bioreactor and waste stream solids concentration. At a constant flux of 2.75 L/m2/hour, the transmembrane pressure and the fouling rate remained low and relatively constant over the course of operation, despite reduced mass flow of solids. The performance of the membrane was attributed to the fouling minimizing protocol that consisted of regular maintenance cleaning, a relaxed mode of operation, and continuous gas sparging.\ }, author = {Wayne Parker and Priyanka Joshi} } @article {27287, title = {Characterization of Sulfur in Raw and Anaerobically Digested Municipal Wastewater Treatment Sludges}, journal = {Water Environment Research }, volume = {85}, year = {2013}, abstract = {A microwave-enhanced acid digestion method that was integrated with inductively coupled plasma-atomic emission spectrometry was developed and validated for determining total, soluble, and precipitated sulfur in wastewater treatment sludges. The coefficient of variation of this method was less than 4.0\%. The recovery of dosed sulfur from sludge samples was between 97.1\% and 100.5\%. The composition of sulfur in primary and waste-activated sludge (WAS) before and after anaerobic digestion at 35 and 55 {\textdegree}C was characterized by employing this developed method. There was not an apparent relationship between the precipitated sulfur and nonsoluble iron concentrations in sludges. Raw WAS had a more consistent organic sulfur fractionation because of its relatively homogeneous composition. The organic-sulfur-containing components (proteins) of WAS had reduced degradability as compared with that in primary sludge during anaerobic digestion. Digestion at 55 {\textdegree}C increased solubilization but not ultimate conversion of organic sulfur in sludge.}, author = {Wayne Parker and Weiwei Du} } @article {27288, title = {An Assessment of the Feasibility of Employing Biochemical Acidogenic Potential Tests for Characterizing Anaerobic Biodegradability of Raw and Pretreated Waste Activated Sludge}, journal = {Water Environment Research }, volume = {84}, year = {2012}, abstract = {The potential to use the results of biochemical acid potential (BAP) tests to predict the ultimate digestibility of raw and pretreated waste activated sludge (WAS) was investigated. The ultimate methane production from biochemical methane potential (BMP) tests on raw and pretreated samples which spanned a range of biodegradability proved linearly related to the volatile fatty acid (VFA) and soluble chemical oxygen demand (COD) production in corresponding BAP tests. In addition, a linear relationship between NH4-N production in the BMP and BAP tests was observed. Despite the linear nature of the relationships, the ratio of the production of methane in the BMP tests to the production of VFAs in the BAP tests varied with the biodegradability of the sludge samples. Waste Activated Sludge samples with low digestibility had ultimate yields of CH4\ that were greater than the VFA yields in BAP tests, whereas sludge samples with high digestibility had lower yields of CH4\ than the corresponding VFA yields. This trend contrasted with the NH4\ results, in which the yields in the BAP tests were consistently less than those observed in the BMP tests. It was hypothesized that the varying relationship between CH4\ and VFA yields was because of the inhibition of anaerobic oxidation of long-chain fatty acids (LCFAs) in the BAP tests. Long-chain fatty acids would be converted to CH4\ in BMP tests but produced as digestion intermediates in the BAP tests and were not measured as part of the VFA yield. Hydrogen and acetate were identified as the two most likely intermediates that would accumulate in the BAP tests (which would cause inhibition). A stoichiometric model to facilitate the development of an improved understanding of the biodegradation processes in the BAP and BMP tests was assembled. When the model was applied to the BAP tests the anaerobic oxidation of LCFAs and propionate and methanogenesis were excluded from the model. The model was employed to estimate the extent of degradation of lipids, carbohydrates, and proteins in the batch tests as a function of the ultimate biodegradability of the sludge samples. On the basis of model fitting, it was determined that the degradation of lipids in BMP tests decreased, whereas the degradation of carbohydrates and proteins increased as the digestibility of the sludge samples increased. The varying ratio of lipid to protein and carbohydrate degradability with increasing digestibility of the sludge samples describes the relationship between VFA production and CH4\ production in the BAP, and BMP tests, respectively.}, author = {Wayne Parker and Peiman Kianmahr and Peter Soto} } @article {27290, title = {Characterization of Natural Ventilation in Wastewater Collection Systems}, journal = {Water Environment Research }, volume = {83}, year = {2011}, abstract = {The purpose of the study was to characterize natural ventilation in full-scale gravity collection system components while measuring other parameters related to ventilation. Experiments were completed at four different locations in the wastewater collection systems of Los Angeles County Sanitation Districts, Los Angeles, California, and the King County Wastewater Treatment District, Seattle, Washington. The subject components were concrete gravity pipes ranging in diameter from 0.8 to 2.4 m (33 to 96 in.). Air velocity was measured in each pipe using a carbon-monoxide pulse tracer method. Air velocity was measured entering or exiting the components at vents using a standpipe and hotwire anemometer arrangement. Ambient wind speed, temperature, and relative humidity; headspace temperature and relative humidity; and wastewater flow and temperature were measured. The field experiments resulted in a large database of measured ventilation and related parameters characterizing ventilation in full-scale gravity sewers. Measured ventilation rates ranged from 23 to 840 L/s. The experimental data was used to evaluate existing ventilation models. Three models that were based upon empirical extrapolation, computational fluid dynamics, and thermodynamics, respectively, were evaluated based on predictive accuracy compared to the measured data. Strengths and weaknesses in each model were found and these observations were used to propose a concept for an improved ventilation model.}, author = {Wayne Parker and Matthew Ward and Richard Corsi and Robert Morton and Tom Knapp and Dirk Apgar and Chris Quigley and Chris Easter and Jay Witherspoon and Amit Pramanik} } @article {27291, title = {Predicting the Degradability of Waste Activated Sludge}, journal = {Water Environment Research }, volume = {81}, year = {2009}, abstract = { }, author = {Wayne Parker and Richard Jones and Henry Zhu and Dwight Houweling and Sudhir Murthy} } @article {27293, title = {Biosolids and Sludge Management}, journal = {Water Environment Research }, volume = {79}, year = {2007}, author = {Wayne Parker and Jianpeng Zhou and Shonali Laha} } @article {27295, title = {Biosolids and Sludge Management}, journal = {Water Environment Research }, volume = {78}, year = {2006}, author = {Wayne Parker and Shonali Laha and Jianpeng Zhou} } @article {27294, title = {Steam-Explosion Pretreatment for Enhancing Anaerobic Digestion of Municipal Wastewater Sludge}, journal = {Water Environment Research }, volume = {78}, year = {2006}, author = {Wayne Parker and Marcela Dereix and Kevin Kennedy} } @article {27296, title = {Biosolids and Sludge Management}, journal = {Water Environment Research }, volume = {77}, year = {2005}, author = {Wayne Parker and Shonali Laha} } @article {27297, title = {Biosolids and Sludge Management}, journal = {Water Environment Research }, volume = {76}, year = {2004}, author = {Wayne Parker and Shonali Laha} } @article {27303, title = {Enhanced scrubbing of chlorinated compounds from air streams}, journal = {Environmental Progress}, volume = {19}, year = {2004}, abstract = {

This paper addresses an investigation of mass transfer issues associated with an innovative hybrid process to treat air streams containing chlorinated organics. Three target compounds [dichloromethane (DCM), carbon tetrachloride (CT) and tetra chloroethylene (PCE)] we re evaluated to assess a range of chemical and physical properties.

Vegetable oil was found to be an effective scrubbing solution in removing the target compounds from the air streams and was employed in continuous flow tests of a bench-scale countercurrent packed co lumn. Removal efficiencies approached 90\% for all three target compounds with gas-liquid flow ratios less than 200.

A gas-liquid mass transfer model was developed and compared to the existing Onda correlations, to characterize mass transfer under various operating conditions when water and vegetable oil were employed as scrubbing solutions. It was found that the Onda correlations did not fit the experimental data of vegetable oil very well. The existing Onda correlations we re modified by assuming that the gas phase resistance was controlling mass transfer.

In order to enhance mass transfer from the oil phase to an aqueous phase a liquid-liquid contacting reactor was proposed. The results of the liquid-liquid reactor suggested that mass transfer could be achieved for compounds that were not highly hydrophobic.

}, author = {Wayne Parker and Jodi Johnson and Kevin Kennedy} } @article {27298, title = {Biosolids and Sludge Management}, journal = {Water Environment Research }, volume = {75}, year = {2003}, author = {Wayne Parker and Shonali Laha} } @article {27299, title = {Perfectionism and Suicidal Preoccupation}, journal = {Journal of Personality}, volume = {64}, year = {1996}, abstract = {One hundred twenty-nine undergraduate students were assessed for suicidal preoccupation, using the Alabama Adolescent Health Survey (AAHS) and selected cards from the Thematic Apperception Test (TAT). They were also administered the Multidimensional Perfectionism Scale (MPS) to assess perfectionistic tendencies. Objective scoring of the TAT was found to be highly reliable. Canonical correlational analyses were nonsignificant for a relationship between perfectionism and suicidal themes on the TAT. However, the more direct questions of the AAHS relating to suicide were significantly related to perfectionism. Results suggest that passive perfectionists who procrastinate out of fear of making mistakes are more likely to be preoccupied with suicide, unlike perfectionists whose strivings produce achievement. High personal standards and parental expectations do not appear related to suicidal preoccupations.}, author = {Wayne Parker and Karen Kittler Adkins} } @article {27283, title = {Preliminary assessment of the removal of volatile organic compounds in a biological selector process}, journal = {Water Environment Research }, volume = {67}, year = {1995}, abstract = {The fate of selected volatile organic compounds (VOCs) in anoxic or anaerobic selectors was investigated at pilot scale. Tetrachloroethylene, 1,4-dichlorobenzene, and 1,3,5-trimethylbenzene were consistently removed at efficiencies in excess of 30\%. The removals observed in this study were highly compound specific. Compounds with similar chemical structures such as toluene and 1,3,5-trimethylbenzene displayed substantially different behavior. The selector biomass concentration and hydraulic retention time were found to have little apparent effect on the VOC removal efficiencies. However, the results were confounded by a change in wastewater temperature that also influenced the loading of nitrate on the selector. The results of these experiments demonstrate the potential of selector technologies for reducing the mass loading of VOCs to aeration basins. The lower mass loadings should reduce the mass of aerobically recalcitrant VOCs that will be stripped to the atmosphere.}, author = {Wayne Parker and Hugh Monteith and Henryk Melcer} }