John Churchley - Academia.edu (original) (raw)
Papers by John Churchley
Proceedings of the Water Environment Federation, 2000
Environmental Technology, Dec 1, 2006
Coloration Technology, 2000
The bioelimination of a series of hydrolysed reactive dyes of known chemical structure has been d... more The bioelimination of a series of hydrolysed reactive dyes of known chemical structure has been determined using a new, rapid and robust laboratory method and a chemometric analysis conducted on the bioelimination results. The level of bioelimination varies from 0% up to only 25% and the chemometric analysis indicates that if either the number of aromatic rings increases or the number of 2-hydroxyethylsulphone groups decreases, then the bioelimination increases. To maximise the bioelimination of reactive dyes, large, planar triazine-based dyes should be used.
Wastewater treatment: Evaluation and Implementation, 1994
Water Research, 2007
The primary driver for a successful biological nutrient removal (BNR) is the availability of suit... more The primary driver for a successful biological nutrient removal (BNR) is the availability of suitable carbon source, mainly in the form of volatile fatty acids (VFA). Several methods have been examined to increase the amount of VFAs in wastewater. This study investigates the mechanism of mechanical disintegration of thickened surplus activated sludge (SAS) by a deflaker technology for the production of organic matter. This equipment was able to increase the soluble carbon in terms of VFA and soluble chemical oxygen demand (SCOD) with the maximum concentration to be around 850 and 6530 mg l-1 , for VFA and SCOD, respectively. The particle size was reduced from 65.5 μm to 9.3 μm after 15 minutes of disintegration with the simultaneous release of proteins (1550 mg l-1) and carbohydrates (307 mg l-1) indicating floc disruption and breakage. High performance size exclusion chromatography (HPSEC) investigated the disintegrated sludge and confirmed that the deflaker was able to destroy the flocs releasing polymeric substances that are typically found outside of cells. When long disintegration times were applied (≥10 minutes or ≥9000 kJ kg-1 TS of specific energy) smaller molecular size materials were released to the liquid phase, which are considered to be found inside the cells indicating cell lysis.
Wastewater treatment: Evaluation and Implementation, 1994
Water Research, 2002
Struvite (MgNH 4 PO 4 Á 6H 2 O) fouling was investigated to identify the impact supersaturation a... more Struvite (MgNH 4 PO 4 Á 6H 2 O) fouling was investigated to identify the impact supersaturation and material had on scaling rates. Tests were undertaken at three supersaturation ratios and with three different materials: stainless steel, teflon and acrylic. Impellers consisting of a clasp unit and two corrosion coupons that could be attached were used to mix centrate liquor and precipitation was initiated by the change in pH caused by degassing. Increasing the supersaturation ratio from 1.7 to 5.3 led to a doubling in the scaling rate of stainless-steel coupons. Experiments with acrylic and teflon coupons showed the influence of surface roughness upon scaling propensity. Coarsely roughened coupons following 40 h of mixing had a mass of 413 mg of struvite attached compared to smooth coupons that had a mass of 240 mg attached. Material did have an influence upon struvite fouling but this influence diminished with increasing surface roughness.
Environmental Toxicology and Chemistry, 2012
Environmental Technology, 2001
Struvite in wastewater treatment plants was identified as early as 1939. Problems with struvite f... more Struvite in wastewater treatment plants was identified as early as 1939. Problems with struvite formation date back to the 1960s when it was noticed at the Hyperion treatment plant, Los Angeles. Operators at the plant noticed crystalline deposits on the underside of post digestion screens. The digested sludge stream was diluted and it was thought the problem was solved, until five years later when the normal gravity flow of digested sludge had decreased to such a stage that pumping was required. This paper reports the findings of a series of experiments undertaken to identify the potential of recovering struvite from sludge liquors. Seven sludge treatment works (STW) have been investigated including one detail. A number of the works has the potential to form over 100 mg l(-1) of struvite.
Environmental Science & Technology, 2012
The prediction of risks posed by pharmaceuticals and personal care products in the aquatic enviro... more The prediction of risks posed by pharmaceuticals and personal care products in the aquatic environment 15 now and in the future is one of the top 20 research questions regarding these contaminants following 16 growing concern for their biological effects on fish and other animals. To this end it is important that 17 areas experiencing the greatest risk are identified, particularly in countries experiencing water stress, 18 where dilution of pollutants entering river networks is more limited. This study is the first to use Page 2 of 33 ACS Paragon Plus Environment Environmental Science & Technology hydrological models to estimate concentrations of pharmaceutical and natural steroid estrogens in a 20 water stressed catchment in South Australia alongside a UK catchment and to forecast their 21 concentrations in 2050 based on demographic and climate change predictions. The results show that 22 despite their differing climates and demographics, modeled concentrations of steroid estrogens in 23 effluents from Australian sewage treatment works and a receiving river were similar to those observed 24 in the UK and Europe, exceeding the combined estradiol equivalent's predicted no effect concentration 25 for feminization in wild fish. Furthermore, by 2050 a moderate increase in estrogenic contamination 26 and the potential risk to wildlife was predicted with up to a twofold rise in concentrations. 27
Environmental Health Perspectives, 2008
On 3 October 2007, 40 participants with diverse expertise attended the workshop Tamiflu and the E... more On 3 October 2007, 40 participants with diverse expertise attended the workshop Tamiflu and the Environment: Implications of Use under Pandemic Conditions to assess the potential human health impact and environmental hazards associated with use of Tamiflu during an influenza pandemic. Based on the identification and risk-ranking of knowledge gaps, the consensus was that oseltamivir ethylester-phosphate (OE-P) and oseltamivir carboxylate (OC) were unlikely to pose an ecotoxicologic hazard to freshwater organisms. OC in river water might hasten the generation of OCresistance in wildfowl, but this possibility seems less likely than the potential disruption that could be posed by OC and other pharmaceuticals to the operation of sewage treatment plants. The workgroup members agreed on the following research priorities: a) available data on the ecotoxicology of OE-P and OC should be published; b) risk should be assessed for OC-contaminated river water generating OC-resistant viruses in wildfowl; c) sewage treatment plant functioning due to microbial inhibition by neuraminidase inhibitors and other antimicrobials used during a pandemic should be investigated; and d) realistic worst-case exposure scenarios should be developed. Additional modeling would be useful to identify localized areas within river catchments that might be prone to high pharmaceutical concentrations in sewage treatment plant effluent. Ongoing seasonal use of Tamiflu in Japan offers opportunities for researchers to assess how much OC enters and persists in the aquatic environment.
Water Science and Technology
Textile dyeing within the Severn Trent Region produces highly coloured wastewater. This dyewaste ... more Textile dyeing within the Severn Trent Region produces highly coloured wastewater. This dyewaste is usually discharged untreated to foul sewer. Conventional treatment at the receiving sewage treatment works removes little colour resulting in colouration of effluents and rivers in certain areas. The regulatory body (N.R.A.) has set strict colour standards on 5 of S.T.W.L. sewage works. These standards are based on a River Quality Objective (R.Q.O.). Methods of removing colour are reviewed. The full scale ozone colour removal plant at Leek S.T.W. is described and early operating data is given. Good colour removal has been obtained, but compliance with the consent has been 89.7% and not the 100% required. Data is presented to indicate that the R.Q.O. does not adequately take natural colour into account. Target aborbances at 400 and 450 nm are thus too low to be practicable for the derived sewage effluent consents.
International Journal of Chemical Engineering, 2013
The pollution of water sources by endocrine disrupting compounds (EDCs) and pharmaceutical and pe... more The pollution of water sources by endocrine disrupting compounds (EDCs) and pharmaceutical and personal care products (PPCPs) is a growing concern, as conventional municipal wastewater treatment systems are not capable of completely removing these contaminants. A continuous stir tank reactor incorporating a modified polyacrylonitrile (PAN) catalyst and dosed with hydrogen peroxide in a heterogeneous Fenton’s process was used at pilot scale to remove these compounds from wastewater that has undergone previous treatment via a conventional wastewater treatment system. The treatment system was effective at ambient temperature and at the natural pH of the wastewater. High levels of both natural and synthetic hormones (EDCs) and PPCPs were found in the effluent after biological treatment of the wastewater. The treatment system incorporating the modified PAN catalyst/H2O2decomposed >90% of the EDCs and >40% of PPCPs using 200 mgL−1H2O2, 3 hr residence time. The estrogenic potency EE2...
Water Science and Technology, 1996
Severn Trent as part of their wastewater development strategy have built a full scale biological ... more Severn Trent as part of their wastewater development strategy have built a full scale biological nutrient removal plant at Stratford-upon-Avon, where Mainstream and Sidestream Phostrip® processes are studied. The plant, designed to treat 5000 m3/d, was commissioned in November 1993 and whilst the Phostrip® plant has consistently achieved the target level of 1 mg/l P, the UCT plant is able to achieve this standard only with the addition of fermenter liquor containing sufficient concentrations of Short Chain Fatty Acids (SCFA). Enforced decommissioning of the sludge fermenter provided an interesting period of study when both the anaerobic phosphorus release and aerobic phosphorus uptake deteriorated as the concentration of combined phosphate in the polyP biomass fell steadily to a level of less than 3% phosphorus. Effluent performance was restored following subsequent recommissioning of the sludge fermenter and the authors conclude that the Stratford sewage, despite having a BOD:P ratio greater than 20 and considered a strong sewage, still required the addition of SCFA for consistent phosphorus removal. The authors conclude that SCFA addition to mainstream Enhanced Biological Phosphorus Removal Plants (EBPR) is required to maintain the poly P sludge in satisfactory condition to both release and uptake phosphorus and meet the UWWTD standard of 1 mg/l P.
Chemical Speciation and Bioavailability, 2005
Water and Environment Journal, 1995
The EC urban waste water treatment Directive will lead to some sewage-treatment works in the UK h... more The EC urban waste water treatment Directive will lead to some sewage-treatment works in the UK having to remove nitrogen and phosphorus. The paper reviews the basic biological processes which are available for retrofitting existing activated-sludge plants to achieve this removal, and then points to some of the problems which are encountered with these processes in other countries. The authors make suggestions as to how these problems can be overcome in design and operation. The paper also provides a cost comparison of different ways of uprating an existing nitrifying activated-sludge plant to achieve nitrification/ denitrification and phosphorus removal.
Ozone: Science & Engineering, 1998
The problems caused by discharges of colored dye waste into the sewer are described. Coloration o... more The problems caused by discharges of colored dye waste into the sewer are described. Coloration of the River Churnet by the Leek Sewage Treatment Works (STW) effluent necessitated the setting of color discharge consent conditions by the National Rivers Authority (now the Environment Agency). These and other tightened consent conditions led to the planning of a major works extension to
Proceedings of the Water Environment Federation, 2000
Environmental Technology, Dec 1, 2006
Coloration Technology, 2000
The bioelimination of a series of hydrolysed reactive dyes of known chemical structure has been d... more The bioelimination of a series of hydrolysed reactive dyes of known chemical structure has been determined using a new, rapid and robust laboratory method and a chemometric analysis conducted on the bioelimination results. The level of bioelimination varies from 0% up to only 25% and the chemometric analysis indicates that if either the number of aromatic rings increases or the number of 2-hydroxyethylsulphone groups decreases, then the bioelimination increases. To maximise the bioelimination of reactive dyes, large, planar triazine-based dyes should be used.
Wastewater treatment: Evaluation and Implementation, 1994
Water Research, 2007
The primary driver for a successful biological nutrient removal (BNR) is the availability of suit... more The primary driver for a successful biological nutrient removal (BNR) is the availability of suitable carbon source, mainly in the form of volatile fatty acids (VFA). Several methods have been examined to increase the amount of VFAs in wastewater. This study investigates the mechanism of mechanical disintegration of thickened surplus activated sludge (SAS) by a deflaker technology for the production of organic matter. This equipment was able to increase the soluble carbon in terms of VFA and soluble chemical oxygen demand (SCOD) with the maximum concentration to be around 850 and 6530 mg l-1 , for VFA and SCOD, respectively. The particle size was reduced from 65.5 μm to 9.3 μm after 15 minutes of disintegration with the simultaneous release of proteins (1550 mg l-1) and carbohydrates (307 mg l-1) indicating floc disruption and breakage. High performance size exclusion chromatography (HPSEC) investigated the disintegrated sludge and confirmed that the deflaker was able to destroy the flocs releasing polymeric substances that are typically found outside of cells. When long disintegration times were applied (≥10 minutes or ≥9000 kJ kg-1 TS of specific energy) smaller molecular size materials were released to the liquid phase, which are considered to be found inside the cells indicating cell lysis.
Wastewater treatment: Evaluation and Implementation, 1994
Water Research, 2002
Struvite (MgNH 4 PO 4 Á 6H 2 O) fouling was investigated to identify the impact supersaturation a... more Struvite (MgNH 4 PO 4 Á 6H 2 O) fouling was investigated to identify the impact supersaturation and material had on scaling rates. Tests were undertaken at three supersaturation ratios and with three different materials: stainless steel, teflon and acrylic. Impellers consisting of a clasp unit and two corrosion coupons that could be attached were used to mix centrate liquor and precipitation was initiated by the change in pH caused by degassing. Increasing the supersaturation ratio from 1.7 to 5.3 led to a doubling in the scaling rate of stainless-steel coupons. Experiments with acrylic and teflon coupons showed the influence of surface roughness upon scaling propensity. Coarsely roughened coupons following 40 h of mixing had a mass of 413 mg of struvite attached compared to smooth coupons that had a mass of 240 mg attached. Material did have an influence upon struvite fouling but this influence diminished with increasing surface roughness.
Environmental Toxicology and Chemistry, 2012
Environmental Technology, 2001
Struvite in wastewater treatment plants was identified as early as 1939. Problems with struvite f... more Struvite in wastewater treatment plants was identified as early as 1939. Problems with struvite formation date back to the 1960s when it was noticed at the Hyperion treatment plant, Los Angeles. Operators at the plant noticed crystalline deposits on the underside of post digestion screens. The digested sludge stream was diluted and it was thought the problem was solved, until five years later when the normal gravity flow of digested sludge had decreased to such a stage that pumping was required. This paper reports the findings of a series of experiments undertaken to identify the potential of recovering struvite from sludge liquors. Seven sludge treatment works (STW) have been investigated including one detail. A number of the works has the potential to form over 100 mg l(-1) of struvite.
Environmental Science & Technology, 2012
The prediction of risks posed by pharmaceuticals and personal care products in the aquatic enviro... more The prediction of risks posed by pharmaceuticals and personal care products in the aquatic environment 15 now and in the future is one of the top 20 research questions regarding these contaminants following 16 growing concern for their biological effects on fish and other animals. To this end it is important that 17 areas experiencing the greatest risk are identified, particularly in countries experiencing water stress, 18 where dilution of pollutants entering river networks is more limited. This study is the first to use Page 2 of 33 ACS Paragon Plus Environment Environmental Science & Technology hydrological models to estimate concentrations of pharmaceutical and natural steroid estrogens in a 20 water stressed catchment in South Australia alongside a UK catchment and to forecast their 21 concentrations in 2050 based on demographic and climate change predictions. The results show that 22 despite their differing climates and demographics, modeled concentrations of steroid estrogens in 23 effluents from Australian sewage treatment works and a receiving river were similar to those observed 24 in the UK and Europe, exceeding the combined estradiol equivalent's predicted no effect concentration 25 for feminization in wild fish. Furthermore, by 2050 a moderate increase in estrogenic contamination 26 and the potential risk to wildlife was predicted with up to a twofold rise in concentrations. 27
Environmental Health Perspectives, 2008
On 3 October 2007, 40 participants with diverse expertise attended the workshop Tamiflu and the E... more On 3 October 2007, 40 participants with diverse expertise attended the workshop Tamiflu and the Environment: Implications of Use under Pandemic Conditions to assess the potential human health impact and environmental hazards associated with use of Tamiflu during an influenza pandemic. Based on the identification and risk-ranking of knowledge gaps, the consensus was that oseltamivir ethylester-phosphate (OE-P) and oseltamivir carboxylate (OC) were unlikely to pose an ecotoxicologic hazard to freshwater organisms. OC in river water might hasten the generation of OCresistance in wildfowl, but this possibility seems less likely than the potential disruption that could be posed by OC and other pharmaceuticals to the operation of sewage treatment plants. The workgroup members agreed on the following research priorities: a) available data on the ecotoxicology of OE-P and OC should be published; b) risk should be assessed for OC-contaminated river water generating OC-resistant viruses in wildfowl; c) sewage treatment plant functioning due to microbial inhibition by neuraminidase inhibitors and other antimicrobials used during a pandemic should be investigated; and d) realistic worst-case exposure scenarios should be developed. Additional modeling would be useful to identify localized areas within river catchments that might be prone to high pharmaceutical concentrations in sewage treatment plant effluent. Ongoing seasonal use of Tamiflu in Japan offers opportunities for researchers to assess how much OC enters and persists in the aquatic environment.
Water Science and Technology
Textile dyeing within the Severn Trent Region produces highly coloured wastewater. This dyewaste ... more Textile dyeing within the Severn Trent Region produces highly coloured wastewater. This dyewaste is usually discharged untreated to foul sewer. Conventional treatment at the receiving sewage treatment works removes little colour resulting in colouration of effluents and rivers in certain areas. The regulatory body (N.R.A.) has set strict colour standards on 5 of S.T.W.L. sewage works. These standards are based on a River Quality Objective (R.Q.O.). Methods of removing colour are reviewed. The full scale ozone colour removal plant at Leek S.T.W. is described and early operating data is given. Good colour removal has been obtained, but compliance with the consent has been 89.7% and not the 100% required. Data is presented to indicate that the R.Q.O. does not adequately take natural colour into account. Target aborbances at 400 and 450 nm are thus too low to be practicable for the derived sewage effluent consents.
International Journal of Chemical Engineering, 2013
The pollution of water sources by endocrine disrupting compounds (EDCs) and pharmaceutical and pe... more The pollution of water sources by endocrine disrupting compounds (EDCs) and pharmaceutical and personal care products (PPCPs) is a growing concern, as conventional municipal wastewater treatment systems are not capable of completely removing these contaminants. A continuous stir tank reactor incorporating a modified polyacrylonitrile (PAN) catalyst and dosed with hydrogen peroxide in a heterogeneous Fenton’s process was used at pilot scale to remove these compounds from wastewater that has undergone previous treatment via a conventional wastewater treatment system. The treatment system was effective at ambient temperature and at the natural pH of the wastewater. High levels of both natural and synthetic hormones (EDCs) and PPCPs were found in the effluent after biological treatment of the wastewater. The treatment system incorporating the modified PAN catalyst/H2O2decomposed >90% of the EDCs and >40% of PPCPs using 200 mgL−1H2O2, 3 hr residence time. The estrogenic potency EE2...
Water Science and Technology, 1996
Severn Trent as part of their wastewater development strategy have built a full scale biological ... more Severn Trent as part of their wastewater development strategy have built a full scale biological nutrient removal plant at Stratford-upon-Avon, where Mainstream and Sidestream Phostrip® processes are studied. The plant, designed to treat 5000 m3/d, was commissioned in November 1993 and whilst the Phostrip® plant has consistently achieved the target level of 1 mg/l P, the UCT plant is able to achieve this standard only with the addition of fermenter liquor containing sufficient concentrations of Short Chain Fatty Acids (SCFA). Enforced decommissioning of the sludge fermenter provided an interesting period of study when both the anaerobic phosphorus release and aerobic phosphorus uptake deteriorated as the concentration of combined phosphate in the polyP biomass fell steadily to a level of less than 3% phosphorus. Effluent performance was restored following subsequent recommissioning of the sludge fermenter and the authors conclude that the Stratford sewage, despite having a BOD:P ratio greater than 20 and considered a strong sewage, still required the addition of SCFA for consistent phosphorus removal. The authors conclude that SCFA addition to mainstream Enhanced Biological Phosphorus Removal Plants (EBPR) is required to maintain the poly P sludge in satisfactory condition to both release and uptake phosphorus and meet the UWWTD standard of 1 mg/l P.
Chemical Speciation and Bioavailability, 2005
Water and Environment Journal, 1995
The EC urban waste water treatment Directive will lead to some sewage-treatment works in the UK h... more The EC urban waste water treatment Directive will lead to some sewage-treatment works in the UK having to remove nitrogen and phosphorus. The paper reviews the basic biological processes which are available for retrofitting existing activated-sludge plants to achieve this removal, and then points to some of the problems which are encountered with these processes in other countries. The authors make suggestions as to how these problems can be overcome in design and operation. The paper also provides a cost comparison of different ways of uprating an existing nitrifying activated-sludge plant to achieve nitrification/ denitrification and phosphorus removal.
Ozone: Science & Engineering, 1998
The problems caused by discharges of colored dye waste into the sewer are described. Coloration o... more The problems caused by discharges of colored dye waste into the sewer are described. Coloration of the River Churnet by the Leek Sewage Treatment Works (STW) effluent necessitated the setting of color discharge consent conditions by the National Rivers Authority (now the Environment Agency). These and other tightened consent conditions led to the planning of a major works extension to