I have worked exclusively in the Water Industry for 38 years from working in a laboratory to billion dollar investment program for the design of new water and wastewater treatment plants and brownfield upgrades. I have many publications and am a keen sup[porter of research with academic institutions and research organisations Phone: +61 (0)429202851
Quantification and comparison of the dewatering characteristics of fifteen sewage sludges from a ... more 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.
An increase in reservoir water colour over the last 10 years has been impacting on the ability of... more An increase in reservoir water colour over the last 10 years has been impacting on the ability of water treatment works (WTWs) in the UK to meet THM regulations. The problem is exacerbated in autumn particularly after heavy rainfall. It appears that residual organics are labile precursors to disinfection by-products (DBPs). One WTW was investigated to determine a link between raw water characteristics and reactivity with chlorine. Bulk water parameters were measured but the information obtained was limited. To further characterise the water, samples of reservoir water were fractionated using XAD resins and UF membranes. The resulting fractions were subjected to analysis of dissolved organic carbon (DOC), UV absorbance at 254 nm (UV254), specific UV absorbance (SUVA) defined as the ratio of UV254 to DOC and trihalomethane formation potential (THM-FP). The samples were also characterised using high performance size exclusion chromatography (HPSEC). Both methods of fractionation described here have limitations in explaining the bulk water behaviour. The relationship between SUVA and THM-FP was discussed. HPSEC showed that the size distribution of the resin separated and membrane separated fractions was similar indicating that the molecular weight cut-off (MWCO) of the membranes is not sharp.
Seasonal periods of high rainfall have been shown to cause elevated natural organic matter (NOM) ... more Seasonal periods of high rainfall have been shown to cause elevated natural organic matter (NOM) loadings at treatment works. These high levels lead to difficulties in removing sufficient NOM to meet trihalomethane (THM) standards, and hence better alternative treatments are required. Here three options for the removal of NOM either by optimising current coagulation and pre- or post-coagulation have been
A potable water treatment plant, supplied from a low NOM (natural organic matter), low turbidity ... more A potable water treatment plant, supplied from a low NOM (natural organic matter), low turbidity source with precoagulation and two-stage pressure sand filtration, had a MF (microfiltration) membrane process added to meet UK Water Regulations. An autopsy of the membrane modules showed that despite upstream coagulation/filtration with chlorination, a biofilm of EPS (extracellular polymeric substances) and inorganic particulates had developed. Backwashing under laboratory conditions yielded an almost full recovery. Laboratory-scale modules of fouled fibres from pre-commissioning and post-commissioning were assembled and cleaned. The recovery was modelled and optimized with a response surface experiment using variables of concentration, soak period and temperature. The pre-commissioning fibres were more recovered by longer chemical soak times at higher cleanant concentrations than the post-commissioning fibres. Comparative tests on post-commissioning fibres indicated that full recovery was possible with organic acids. It was concluded that start-up of new membrane plants may involve fouling conditions not necessarily representative of those under routine operating conditions, such that modification to prescribed cleaning operations may be required.
In 2013, hospital-acquired Legionella pneumophila (L. pneumophila) led to illness and death in Qu... more In 2013, hospital-acquired Legionella pneumophila (L. pneumophila) led to illness and death in Queensland, Australia, prompting unprecedented State-wide healthcare potable water microbial sampling. Results revealed pockets of high HPC bacteria and L. pneumophila serogroup (SG) 1 counts state-wide, shedding new light on a previously unrecognized risk. These bacteriological results were part of a program which identified gaps in Queensland healthcare infrastructure water quality management which required attention in order to properly protect public health. These gaps furthermore included potential for the implementation of change in Australian municipal water management as Australian Drinking Water Guidelines (ADWG) do not require, but only recommend quality practices (such as for disinfection effectiveness, turbidity, and secondary disinfectant residual). Key challenges in Queensland water quality which were seen to feed into the problems identified in healthcare infrastructure pota...
The Australian Drinking Water Guidelines (ADWG) directs efforts expended by Australian utilities ... more The Australian Drinking Water Guidelines (ADWG) directs efforts expended by Australian utilities to provide safe, reliable water. It provides guidance in determining the health of supplies, proper treatment for purification and potable needs, and maintenance of water quality through regional and council reticulation schemes. It is also a living document, as evidenced by the recently published revision (NHMRC, NRMMC 2011). Future ADWG revisions are expected to follow patterns similar to other governmental and international guidance and regulatory documents. This manuscript investigates evolutionary changes to non-Australian regulatory practices to help provide an assessment of ADWG's future, and what utilities can do to prepare.
A significant consideration in forward planning for water treatment works design and operation co... more A significant consideration in forward planning for water treatment works design and operation concerns the effectiveness of a filtration plant in providing a barrier to particulates in the low micrometre size range, including Cryptosporidium oocysts. The performance of rapid gravity filtration ...
The fate and removal of permethrin during conventional wastewater treatment were evaluated at pil... more The fate and removal of permethrin during conventional wastewater treatment were evaluated at pilot-plant scale at different concentrations of mixed liquor suspended solids (MLSS) and, hence, different solids retention times (SRT). At feed concentrations of 0.26-0.86 microg L(-1), the permethrin was removed by primary treatment at an efficiency rate of 37%, similar to previously reported data, and from 40% to 83% for secondary treatment, decreasing with decreasing SRT. Comparable ranges, from 37% up to 98%, have been reported for micropollutants with similar physicochemical properties to permethrin, such as galaxolide and tonalide. Little difference in removal was noted between the medium and low MLSS concentrations trials, the main difference in treated effluent permethrin concentration arising on changing from high to medium MLSS levels. This was attributed to the limited acclimatization period employed in these two trials, leading to higher levels of soluble organic matter in the treated water, with which the permethrin appeared to be associated.
The current sources of copper and zinc in municipal wastewaters have been considered, and the cha... more The current sources of copper and zinc in municipal wastewaters have been considered, and the changes in the concentrations and quantities of these two elements entering sewage treatment works over the last three decades have been calculated. The concentrations and quantities of the heavy metals cadmium, chromium, copper, mercury, nickel, lead and zinc, entering UK sewage treatment works, have been reduced by between 50% and 90% during this period. However, the reductions in copper and zinc appear to be at the lower end of these ranges and thus remain a cause for concern, particularly their concentrations in sewage effluents and their potential environmental impacts on receiving waters. Bench studies have been undertaken to predict removals by three types of biological wastewater treatment plants: trickling filters, conventional activated sludge and membrane bioreactors, to determine if any of these processes are more efficacious for the removal of these metals. These results suggest that, despite membrane bioreactor biomass achieving the lowest effluent suspended solids concentration and having the lowest effluent chemical oxygen demand, which is accepted as a surrogate measure of organic chemical chelating ability of the aqueous phase, they produce the highest effluent values for the two metals in this study (copper and zinc). Removals of zinc and copper in biological wastewater treatment processes are probably primarily determined by those factors influencing metal solubility in the biomass matrix.
A potable water treatment plant, supplied from a low NOM (natural organic matter), low turbidity ... more A potable water treatment plant, supplied from a low NOM (natural organic matter), low turbidity source with precoagulation and two-stage pressure sand filtration, had a MF (microfiltration) membrane process added to meet UK Water Regulations. An autopsy of the membrane modules showed that despite upstream coagulation/filtration with chlorination, a biofilm of EPS (extracellular polymeric substances) and inorganic particulates had developed. Backwashing under laboratory conditions yielded an almost full recovery. Laboratory-scale modules of fouled fibres from pre-commissioning and post-commissioning were assembled and cleaned. The recovery was modelled and optimized with a response surface experiment using variables of concentration, soak period and temperature. The pre-commissioning fibres were more recovered by longer chemical soak times at higher cleanant concentrations than the post-commissioning fibres. Comparative tests on post-commissioning fibres indicated that full recovery was possible with organic acids. It was concluded that start-up of new membrane plants may involve fouling conditions not necessarily representative of those under routine operating conditions, such that modification to prescribed cleaning operations may be required.
Quantification and comparison of the dewatering characteristics of fifteen sewage sludges from a ... more 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.
An increase in reservoir water colour over the last 10 years has been impacting on the ability of... more An increase in reservoir water colour over the last 10 years has been impacting on the ability of water treatment works (WTWs) in the UK to meet THM regulations. The problem is exacerbated in autumn particularly after heavy rainfall. It appears that residual organics are labile precursors to disinfection by-products (DBPs). One WTW was investigated to determine a link between raw water characteristics and reactivity with chlorine. Bulk water parameters were measured but the information obtained was limited. To further characterise the water, samples of reservoir water were fractionated using XAD resins and UF membranes. The resulting fractions were subjected to analysis of dissolved organic carbon (DOC), UV absorbance at 254 nm (UV254), specific UV absorbance (SUVA) defined as the ratio of UV254 to DOC and trihalomethane formation potential (THM-FP). The samples were also characterised using high performance size exclusion chromatography (HPSEC). Both methods of fractionation described here have limitations in explaining the bulk water behaviour. The relationship between SUVA and THM-FP was discussed. HPSEC showed that the size distribution of the resin separated and membrane separated fractions was similar indicating that the molecular weight cut-off (MWCO) of the membranes is not sharp.
Seasonal periods of high rainfall have been shown to cause elevated natural organic matter (NOM) ... more Seasonal periods of high rainfall have been shown to cause elevated natural organic matter (NOM) loadings at treatment works. These high levels lead to difficulties in removing sufficient NOM to meet trihalomethane (THM) standards, and hence better alternative treatments are required. Here three options for the removal of NOM either by optimising current coagulation and pre- or post-coagulation have been
A potable water treatment plant, supplied from a low NOM (natural organic matter), low turbidity ... more A potable water treatment plant, supplied from a low NOM (natural organic matter), low turbidity source with precoagulation and two-stage pressure sand filtration, had a MF (microfiltration) membrane process added to meet UK Water Regulations. An autopsy of the membrane modules showed that despite upstream coagulation/filtration with chlorination, a biofilm of EPS (extracellular polymeric substances) and inorganic particulates had developed. Backwashing under laboratory conditions yielded an almost full recovery. Laboratory-scale modules of fouled fibres from pre-commissioning and post-commissioning were assembled and cleaned. The recovery was modelled and optimized with a response surface experiment using variables of concentration, soak period and temperature. The pre-commissioning fibres were more recovered by longer chemical soak times at higher cleanant concentrations than the post-commissioning fibres. Comparative tests on post-commissioning fibres indicated that full recovery was possible with organic acids. It was concluded that start-up of new membrane plants may involve fouling conditions not necessarily representative of those under routine operating conditions, such that modification to prescribed cleaning operations may be required.
In 2013, hospital-acquired Legionella pneumophila (L. pneumophila) led to illness and death in Qu... more In 2013, hospital-acquired Legionella pneumophila (L. pneumophila) led to illness and death in Queensland, Australia, prompting unprecedented State-wide healthcare potable water microbial sampling. Results revealed pockets of high HPC bacteria and L. pneumophila serogroup (SG) 1 counts state-wide, shedding new light on a previously unrecognized risk. These bacteriological results were part of a program which identified gaps in Queensland healthcare infrastructure water quality management which required attention in order to properly protect public health. These gaps furthermore included potential for the implementation of change in Australian municipal water management as Australian Drinking Water Guidelines (ADWG) do not require, but only recommend quality practices (such as for disinfection effectiveness, turbidity, and secondary disinfectant residual). Key challenges in Queensland water quality which were seen to feed into the problems identified in healthcare infrastructure pota...
The Australian Drinking Water Guidelines (ADWG) directs efforts expended by Australian utilities ... more The Australian Drinking Water Guidelines (ADWG) directs efforts expended by Australian utilities to provide safe, reliable water. It provides guidance in determining the health of supplies, proper treatment for purification and potable needs, and maintenance of water quality through regional and council reticulation schemes. It is also a living document, as evidenced by the recently published revision (NHMRC, NRMMC 2011). Future ADWG revisions are expected to follow patterns similar to other governmental and international guidance and regulatory documents. This manuscript investigates evolutionary changes to non-Australian regulatory practices to help provide an assessment of ADWG's future, and what utilities can do to prepare.
A significant consideration in forward planning for water treatment works design and operation co... more A significant consideration in forward planning for water treatment works design and operation concerns the effectiveness of a filtration plant in providing a barrier to particulates in the low micrometre size range, including Cryptosporidium oocysts. The performance of rapid gravity filtration ...
The fate and removal of permethrin during conventional wastewater treatment were evaluated at pil... more The fate and removal of permethrin during conventional wastewater treatment were evaluated at pilot-plant scale at different concentrations of mixed liquor suspended solids (MLSS) and, hence, different solids retention times (SRT). At feed concentrations of 0.26-0.86 microg L(-1), the permethrin was removed by primary treatment at an efficiency rate of 37%, similar to previously reported data, and from 40% to 83% for secondary treatment, decreasing with decreasing SRT. Comparable ranges, from 37% up to 98%, have been reported for micropollutants with similar physicochemical properties to permethrin, such as galaxolide and tonalide. Little difference in removal was noted between the medium and low MLSS concentrations trials, the main difference in treated effluent permethrin concentration arising on changing from high to medium MLSS levels. This was attributed to the limited acclimatization period employed in these two trials, leading to higher levels of soluble organic matter in the treated water, with which the permethrin appeared to be associated.
The current sources of copper and zinc in municipal wastewaters have been considered, and the cha... more The current sources of copper and zinc in municipal wastewaters have been considered, and the changes in the concentrations and quantities of these two elements entering sewage treatment works over the last three decades have been calculated. The concentrations and quantities of the heavy metals cadmium, chromium, copper, mercury, nickel, lead and zinc, entering UK sewage treatment works, have been reduced by between 50% and 90% during this period. However, the reductions in copper and zinc appear to be at the lower end of these ranges and thus remain a cause for concern, particularly their concentrations in sewage effluents and their potential environmental impacts on receiving waters. Bench studies have been undertaken to predict removals by three types of biological wastewater treatment plants: trickling filters, conventional activated sludge and membrane bioreactors, to determine if any of these processes are more efficacious for the removal of these metals. These results suggest that, despite membrane bioreactor biomass achieving the lowest effluent suspended solids concentration and having the lowest effluent chemical oxygen demand, which is accepted as a surrogate measure of organic chemical chelating ability of the aqueous phase, they produce the highest effluent values for the two metals in this study (copper and zinc). Removals of zinc and copper in biological wastewater treatment processes are probably primarily determined by those factors influencing metal solubility in the biomass matrix.
A potable water treatment plant, supplied from a low NOM (natural organic matter), low turbidity ... more A potable water treatment plant, supplied from a low NOM (natural organic matter), low turbidity source with precoagulation and two-stage pressure sand filtration, had a MF (microfiltration) membrane process added to meet UK Water Regulations. An autopsy of the membrane modules showed that despite upstream coagulation/filtration with chlorination, a biofilm of EPS (extracellular polymeric substances) and inorganic particulates had developed. Backwashing under laboratory conditions yielded an almost full recovery. Laboratory-scale modules of fouled fibres from pre-commissioning and post-commissioning were assembled and cleaned. The recovery was modelled and optimized with a response surface experiment using variables of concentration, soak period and temperature. The pre-commissioning fibres were more recovered by longer chemical soak times at higher cleanant concentrations than the post-commissioning fibres. Comparative tests on post-commissioning fibres indicated that full recovery was possible with organic acids. It was concluded that start-up of new membrane plants may involve fouling conditions not necessarily representative of those under routine operating conditions, such that modification to prescribed cleaning operations may be required.
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