scholarly journals Trihalomethane precursor reactivity changes in drinking water treatment unit processes during a storm event

2019 ◽  
Vol 19 (7) ◽  
pp. 2098-2106
Author(s):  
Chelsea W. Neil ◽  
Yingying Zhao ◽  
Amy Zhao ◽  
Jill Neal ◽  
Maria Meyer ◽  
...  

Abstract Source water quality can significantly impact the efficacy of water treatment unit processes and the formation of chlorinated and brominated trihalomethanes (THMs). Current water treatment plant performance models may not accurately capture how source water quality variations, such as organic matter variability, can impact treatment unit processes. To investigate these impacts, a field study was conducted wherein water samples were collected along the treatment train for 72 hours during a storm event. Systematic sampling and detailed analyses of water quality parameters, including non-purgeable organic carbon (NPOC), UV absorbance, and THM concentrations, as well as chlorine spiking experiments, reveal how the THM formation potential changes in response to treatment unit processes. Results show that the NPOC remaining after treatment has an increased reactivity towards forming THMs, and that brominated THMs form more readily than chlorinated counterparts in a competitive reaction. Thus both the reactivity and quantity of THM precursors must be considered to maintain compliance with drinking water standards, a finding that should be incorporated into the development of model-assisted treatment operation and optimization. Advanced granular activated carbon (GAC) treatment beyond conventional coagulation–flocculation–sedimentation processes may also be necessary to remove the surge loading of THM-formation precursors during a storm event.

2020 ◽  
Vol 20 (6) ◽  
pp. 2106-2118
Author(s):  
Kassim Chabi ◽  
Jie Zeng ◽  
Lizheng Guo ◽  
Xi Li ◽  
Chengsong Ye ◽  
...  

Abstract People in remote areas are still drinking surface water that may contain certain pollutants including harmful microorganisms and chemical compounds directly without any pretreatment. In this study, we have designed and operated a pilot-scale drinking water treatment unit as part of our aim to find an economic and easily operable technology for providing drinking water to people in those areas. Our small-scale treatment unit contains filtration and disinfection (UV–C irradiation) stages to remove pollutants from source water. The water quality index was determined based on various parameters such as pH, temperature, dissolved oxygen, nitrate, nitrite, ammonium, phosphorus, dissolved organic carbon and bacteria. Water and media samples after DNA extraction were sequenced using Illumina MiSeq throughput sequencing for the determination of bacterial community composition. After the raw water treatment, the reduction of bacteria concentration ranged from 1 to 2 log10. The average removal of the turbidity, ammonium, nitrite, phosphorus and dissolved organic carbon reached up to 95.33%, 85.71%, 100%, 28.57%, and 45%, respectively. In conclusion, multiple biological stages in our designed unit showed an improvement of the drinking water quality. The designed drinking treatment unit produces potable water meeting standards at a lower cost of operation and it can be used in remote areas.


2005 ◽  
Vol 71 (2) ◽  
pp. 1042-1050 ◽  
Author(s):  
Gerald Sedmak ◽  
David Bina ◽  
Jeffrey MacDonald ◽  
Lon Couillard

ABSTRACT Reoviruses, enteroviruses, and adenoviruses were quantified by culture for various ambient waters in the Milwaukee area. From August 1994 through July 2003, the influent and effluent of a local wastewater treatment plant (WWTP) were tested monthly by a modified U.S. Environmental Protection Agency Information Collection Rule (ICR) organic flocculation cell culture procedure for the detection of culturable viruses. Modification of the ICR procedure included using Caco-2, RD, and HEp-2 cells in addition to BGM cells. Lake Michigan source water for two local drinking water treatment plants (DWTPs) was also tested monthly for culturable viruses by passing 200 liters of source water through a filter and culturing a concentrate representing 100 liters of source water. Reoviruses, enteroviruses, and adenoviruses were detected frequently (105 of 107 samples) and, at times, in high concentration in WWTP influent but were detected less frequently (32 of 107 samples) in plant effluent and at much lower concentrations. Eighteen of 204 samples (8.8%) of source waters for the two DWTPs were positive for virus and exclusively positive for reoviruses at relatively low titers. Both enteroviruses and reoviruses were detected in WWTP influent, most frequently during the second half of the year.


2012 ◽  
Vol 209-211 ◽  
pp. 1981-1985 ◽  
Author(s):  
Dong Sheng Wang ◽  
Xing Peng Zhou ◽  
Xiao Ming Mo ◽  
Yi Wang

During drinking water treatment, the chemical dosing processes, such as coagulant dosing process, ozone dosing process and chlorine dosing process are usually manually operated based on the operator knowledge and experience. However, due to the variations of water quality, water flow and process operational conditions and characteristics of large time-delay and nonlinear for the chemical dosing processes, it is difficult to adjust the chemical dosages in time by operators to keep the treated water quality stable, especially during the periods of rapid and frequent variations of water quality, water flow and process operational conditions. Thus, the improvements of control methods for the chemical dosing processes are essential to the operation of drinking water treatment plants. The Xiangcheng Water Treatment Plant in Suzhou, China has been utilizing the automatic control for chemical dosing processes since February 2012. Automatic controllers are designed respectively for the coagulant dosing process, ozone dosing process and chlorine dosing process. After the implementation of automatic control, operators are not necessary to keep constant attention. In addition, due to the improvements of control accuracies for the chemical dosing processes, the chemical dosages are reduced on the premise of ensuring safe water. Thus, both of the human resource costs and material costs can be saved. The practical control results demonstrate the efficiencies of proposed methods.


2016 ◽  
Vol 17 (2) ◽  
pp. 597-605
Author(s):  
Zhiquan Liu ◽  
Yongpeng Xu ◽  
Xuewei Yang ◽  
Rui Huang ◽  
Qihao Zhou ◽  
...  

The overall purpose was to assess the feasibilities of recycling filter backwash water (FBWW) and combined filter backwash water (CFBWW) in a drinking water treatment plant in south China. The variations of regular water-quality indexes, metal indexes (Al, Mn and Cd), polyacrylamide and disinfection by-product indexes (trihalomethanes and their formation potentials) along with the treatment and the recycling processes were monitored. Results showed the recycling procedure caused increases of turbidity, total solids, ammonia nitrogen (NH3-N), permanganate index (CODMn), and dissolved organic carbon, Al, Mn and Cd concentrations in a mixture of raw water and FBWW or CFBWW compared to those in raw water. However, the recycling procedure had negligible impacts on the qualities of settled water and filtered water because most of the contaminants could be effectively removed by the conventional water treatment process. Although recycling did cause slight increases of NH3-N and CODMn levels in settled water and filtered water, the quality of finished water always conformed to Chinese standards for drinking water quality according to the surveyed indexes in the present study. Thus, it is appropriate to recycle waste streams in water-stressed areas if the source water is well managed and the water treatment processes are carefully conducted.


2008 ◽  
Vol 8 (3) ◽  
pp. 297-304 ◽  
Author(s):  
A. W. C. van der Helm ◽  
L. C. Rietveld ◽  
Th. G. J. Bosklopper ◽  
J. W. N. M. Kappelhof ◽  
J. C. van Dijk

Optimization for operation of drinking water treatment plants should focus on water quality and not on environmental impact or costs. Using improvement of water quality as objective for optimization can lead to new views on operation, design and concept of drinking water treatment plants. This is illustrated for ozonation in combination with biological activated carbon (BAC) filtration at drinking water treatment plant Weesperkarspel of Waternet, the water cycle company for Amsterdam and surrounding areas. The water quality parameters that are taken into account are assimilable organic carbon (AOC), dissolved organic carbon (DOC) and pathogens. The operational parameters that are taken into account are the ozone dosage and the regeneration frequency of the BAC filters. It is concluded that ozone dosage and regeneration frequency should be reduced in combination with application of newly developed insights in design of ozone installations. It is also concluded that a new concept for Weesperkarspel with an additional ion exchange (IEX) step for natural organic matter (NOM) removal will contribute to the improvement of the disinfection capacity of ozonation and the biological stability of the produced drinking water.


2017 ◽  
Vol 18 (1) ◽  
pp. 279-287 ◽  
Author(s):  
E. Bertone ◽  
K. O'Halloran ◽  
M. Bartkow ◽  
K. Mann

Abstract The Mudgeeraba drinking water treatment plant, in Southeast Queensland, Australia, can withdraw raw water from two different reservoirs: the smaller Little Nerang dam (LND) by gravity, and the larger Advancetown Lake, through the use of pumps. Selecting the optimal intake is based on water quality and operators' experience; however, there is potential to optimise this process. In this study, a comprehensive hybrid (data-driven, chemical, and mathematical) intake optimisation model was developed, which firstly predicts the chemicals dosages, and then the total (chemicals and pumping) costs based on the water quality at different depths of the two reservoirs, thus identifying the cheapest option. A second data-driven, probabilistic model then forecasts the volume of the smaller LND 6 weeks ahead in order to minimise the depletion and spill risks. This is important in case the first model identifies this reservoir as the optimal intake solution, but this could lead in the long term to depletion and full reliance on the electricity-dependent Advancetown Lake. Both models were validated and proved to be accurate, and with the potential for substantial monetary savings for the water utility.


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