A bench-scale evaluation of different treatment options to produce bio-stable drinking water (original) (raw)
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Journal of Water Process Engineering, 2020
Saigon river is the primary water supply source for Ho Chi Minh City, Vietnam. Currently, the formation of harmful disinfectant by-products (DBPs) in the piped water is elevating due to the increase in both organic matter pollution in Saigon river and chloride usage at water treatment plants (WTPs). To provide safe drinking water, the WTPs should upgrade their existing conventional surface water treatment technology to reduce DBP precursors and chlorine consuming substances efficiently. In this study, the long-term performance of a pilot system, including a biofiltration-ozonation unit and a biological activated carbon (BAC) filter in removing these compounds was evaluated. Different from other studies, a tricking filter (TF) was placed before a low-dose ozone contactor for water pretreatment. By partially returning the ozonated water to the TF, the removal of dissolved organic carbon (DOC), which contains DBP precursors, in the TF-ozonation unit was doubled. Over two months operated with highly fluctuated river water quality in the rainy season, the pilot systems stably removed 50 % of DOC, 71 % of trihalomethane formation potential (THMFP), 71 % of Fe 2+ , and 74 % of N-NH 4 +. The TFozonation unit was effective in removing DOC, THMFP, and NH 4 + , while the BAC filter was more effective in removing Fe 2+. If implemented, this system can replace the pre-chlorination process accounting for 74 % of daily chlorine consumption at Tan Hiep WTP. The obtained results indicate that retrofitting WTPs with the tested processes can provide safe drinking water for Ho Chi Minh City residents in the future.
Environmental Health Engineering and Management
Background: Ozone can be used as a single technology or in combination with other processes to improve the coagulation- flocculation or biodegradability in order to remove pollutants in natural water treatment. Methods: In this study, the effects of pre-ozonation with coagulant substances on the quality parameters of drinking water were investigated using humic acid, kaolin, clay, and green algae in a pilot scale. This study was conducted under laboratory conditions (at both acidic and alkaline pH in different dosages of ozone and coagulant at ozone contact time with simulated water sample (5-20 minutes) in different scenarios). Results: The highest removal efficiency of parameters in the state of pre-ozonation alone and preozonation with a coagulant was observed at contact time of 20 minutes, ozone dosage of 5 g/h, coagulant dosage of 25 mg/L, at alkaline pH along with a decrease in temperature. So that, the average removal rate of turbidity, total organic carbon (TOC), color, and ...
International Journal of Environmental Research and Public Health, 2018
High cyanobacteria-derived dissolved organic carbon (DOC) in source water can cause drinking water quality to deteriorate, producing bad taste, odor, toxins, and possibly elevated levels of disinfection byproduct (DBP) precursors. Conventional water treatment processes do not effectively remove algal organic substances. In this study, rapid-sand-filtration effluent from a water treatment plant on Kinmen Island, where serious cyanobacterial blooms occurred, was used to evaluate the DOC- and DBP-removal efficiency of ozonation and/or biofiltration. To simulate a small-scale water distribution system following water treatment, 24 h simulated distribution system (SDS) tests were conducted. The following DBPs were analyzed: trihalomethanes (THMs), haloacetic acids (HAAs), haloacetonitriles (HANs), and trichloronitromethane (TCNM). Applying biological activated-carbon filtration (BAC) on its own achieved the greatest reduction in SDS-DBPs. Ozonation alone caused adverse effects by promoti...
Water
This article presents results of research which aimed to assess the impact of biofiltration processing on the biological stability of water. Effectiveness of biogenic substances removal (C, N, P) and bacteriological quality of water after the biofiltration process were discussed. The research was carried out on a semi-technical scale on natural underground water rich in organic compounds. A filter with a biologically active carbon (BAC) bed was used for the research. Despite the low water temperature of between 9–12 °C, there was a high efficiency of organic matter removal—33–70%. The number of mesophilic and psychrophilic bacteria in the water before and after the biofiltration process was comparable (0–23 CFU/mL) and met the requirements for drinking water. No E. coli was detected in the water samples. The biological material washed out of the filter bed did not cause deterioration of water quality which proved that the operating parameters of the biofilters were properly chosen, ...