Pharmaceuticals and personal care products (PPCPs), endocrine disrupting compounds (EDCs) and disinfection by-products are suspected to have potential adverse impact on humans and hence their elimination during drinking water treatment is often desired or regulated. Based on pilot-plant experiments with three raw water sources, conventional treatment poorly removed the selected PPCPs and EDCs, while ozone/H2O2 and UV/H2O2 (both) with conventional treatment effectively removed PPCPs and EDCs. In most of the experiments, ozone/H2O2 + conventional treatment additionally removed THM formation potentials (THM-FPs) compared to those of conventional treatment. However, UV/H2O2 treatment was found to increase THM-FPs compared to conventionally treated water.

Although potential risk of pharmaceuticals and personal care products (PPCPs) and endocrine disrupting compounds (EDCs) and trihalomethanes to humans is small or unconfirmed, it is advisable to remove these wastewater-related contaminants to increase public confidence and acceptance as a precautionary principle and consequently their elimination or reduction during drinking water treatment is warranted. Experiments were conducted using the dual train pilot-scale conventional treatment plant with ozone and ultraviolet/hydrogen peroxide (UV/H2O2) with three different raw water sources. Reductions of trihalomethanes-formation potentials (THM-FPs) were 8–52%. Ozone was found to decrease THM-FPs while UV/H2O2 was found to increase THM-FPs in most of the experiments under experimental conditions. Conventional treatment poorly removed the selected PPCPs and EDCs while ozone + conventional treatment provided excellent removal. Conventional + UV/H2O2 treatment also demonstrated effective removal. However, removal of PPCPs and EDCs by conventional + UV/H2O2 treatment provided lower efficacy for Sites B and C, likely due to the presence of scavengers such as organics, bicarbonates, carbonates and particles.

Manganese (Mn) and iron (Fe) are typical treatment issues for small drinking water systems using a groundwater source. Although Mn and Fe are not regulated, their aesthetic limits are 0.05 mg/L and 0.3 mg/L in treated water, respectively. Despite these objectives, treated water acceptability would reduce if Mn and Fe levels were observed in treated water. Dissolved organic carbon (DOC) must also be monitored as it is a precursor of disinfection by-products.

Pre-coagulation ozonation has been reported to be effective in drinking water treatment processes. Limited data are available on the impact of advanced oxidation processes (AOPs) on Lake Huron water which serves as a primary source of drinking water for many communities around the Great Lakes region. Impact of ozone/hydrogen peroxide based AOP on Lake Huron water was studied. The results show that AOPs can achieve higher particles removal in finished water and deliver improved filtered water turbidity compared to the conventional treatment process. Sharp decline in ultraviolet absorbance at 254 nm (UV254) was observed immediately following AOP treatment while only minimal overall decrease in dissolved organic carbon (DOC) was achieved.

The application of pre-coagulation ozone in drinking water treatment to provide primary disinfection, has an impact on coagulation and flocculation, and needs to be evaluated further for cold water temperatures, especially when accompanied by episodes of high alkalinity and dissolved organic carbon (DOC). Ozone application to raw water, prior to the addition of coagulants and coagulant aides, was shown to reduce coagulant and coagulant aide doses, and improve settled and filtered water turbidity. The impact on particle count was also noticeable, filtered water particle count was reduced after the application of pre-coagulation ozonation. Pilot-scale experiments were conducted at the Walkerton Clean Water Centre, Walkerton, Ontario, Canada, to investigate the effect of pre-coagulation ozonation, on filtered water turbidity, particle count, and filter performance, during periods when water temperatures could be lower than 5 degrees C.

Pharmaceuticals, personal care products (PPCPs), endocrine disrupting compounds (EDCs), and disinfectant by-products (DBPs) in drinking water are all associated with potential health implications that warrant their removal and formation prevention during drinking water treatment. This work presents the results of several pilot scale studies carried out using; a) dual train conventional treatment processes of coagulation, flocculation, sedimentation, filtration (conventional); and b) (multistage) slow sand filtration (SSF); both coupled with ozone and advanced oxidation processes (AOPs) such as ozone/H₂O₂ and UV/H₂O₂ using natural water from three different sources. Removal of selected PPCPs and EDCs (as a group) was limited (on average 30%) by conventional treatment. On the contrary, ozone/H₂O₂ plus conventional was the most effective process (average of about 97%) to remove the selected PPCPs and EDCs, followed closely by ozone along with conventional treatment which was also very effective; however, at a slightly lower percent (average 95%) removal. Overall, ozone/H₂O₂ or ozone followed by conventional was very effective, irrespective of the raw water quality. However, the effectiveness of conventional treatment plus UV/H₂O₂ AOP was varied by raw water quality, resulting in reduced efficiency for lower raw water quality containing higher organics, bicarbonates, carbonates and particles. The average removal of PPCPs and EDCs with conventional plus UV/H₂O₂ treatment was about 86%. Experiments involving ozone or ozone/H₂O₂ followed by SSF also showed relatively high removals of target contaminants. On average, the removal rates of PPCPs and EDCs were around 95-100% for the combined processes. In comparison, stand-alone ozone or ozone/H₂O₂ showed removals of around 77% of PPCPs and EDCs. Reduction of disinfection by-products formations, measured as THM-FP (trihalomethanes formation potential), was also investigated over the course of all pilot studies and for each of the treatment scenarios. In most experiments, application of ozone/H₂O₂ and ozone alone upstream of the conventional led to additional reductions in THM-FPs as compared to that of the standalone conventional treatment. However, in most experiments, UV/H₂O₂, when applied downstream of the conventional process, increased THM-FPs of the conventionally treated water. SSF process showed to be effective and reduced 71% of THM-FPs.