Study On Ordor Control Technologies Of Drinking Water

To solve the troublesome ordor problem of drinking water in S city during the flooding seasons, field campaign was firstly conducted in S Reservoir and A water plant to determine the types and concentrations of odorant and to evaluate the effectiveness of removing odorants by conventional water treatment process. Aiming at the target odorantsin the source water, performace of removing odorants by oxidation, absorption, aeration and combined processes was investigated experimentally; dynamic models for removing odorants by oxidation, absorption and aeration processes were developed, the effectiveness of removing odorants by different processes was satisfactorily predicted; proper ordor control technologies were selected based on the results of technical and economic analysis. The main research results are as follows:(1)The main odorants are 2-MIB with a concentration range of 7.06-136.32 ng/L and GSM with a concentration range of 0-93.98 ng/L, the spatial distributions of 2-MIB and GSM were not uniform in the reservoir, most of odorants existed in the surface water layer near the dam, and the conventional water treatment processes of A water plant was poor at removing odorants.(3)Removal rates of GSM and 2-MIB gradually increased with the dose of Potassium Permanganate(KMnO4) and oxidation time. Under odorant concentrations of 50~200ng/L, removal rates of odorants by oxidation with KMnO4 under stirred condition were roughly 80~100%, and the net removal rates by only oxidation with KMnO4 were about 20%. Compared with 2-MIB, GSM was easily oxidized with KMnO4. The effectiveness of removing odorants was affected by source water quality.(4)Removal rates of GSM and 2-MIB increased with the dose of chlorine dioxide(ClO2) and oxidation time, GSM was easily oxidized with chlorine dioxide than 2-MIB. Chlorine dioxide was stronger at removing odorants than KMnO4 under similar oxidation conditions.(5)Under fixed concentrations of GSM and 2-MIB, the absorption rates and removal rates of powdered activated carbon(PAC) increased with the dose of PAC, performance of adsorbing GSM with PAC was better than 2-MIB under similar conditions, and it was also influenced by the source water quality.(6)Performance of purging GSM by aeration was better than 2-MIB, purging rates of odorants increased with the ratio of air to water but not with the initial odorant concentrations, the maximum odorant concentrations were determined under different ratios of air to water.(7)Different dynamic models were developed for removing odorants by oxidation with KMnO4, absorption with PAC, and purging by aeration,the effectiveness of removing odorants was well predicted with the developed dynamic models, and the proper process parameters were also determined.(8)Technical and economic analysis were performed for the oxidation with KMnO4, oxidation with ClO2, absorption with PAC, purging by aeration, oxidation with KMnO4 combined with absorption with PAC and purging by aeration combined with absorption with PAC processes. Under low concentrations of GSM or 2-MIB of source water,oxidation with KMnO4 or chlorine dioxide is suggested, the dosing location can be at the raw water pump station. Under high concentrations of GSM or 2-MIB of source water,oxidation with KMnO4 combined with absorption with PAC is suggested, purging by aeration combined with absorption with PAC can also be used if the cost of air supply is low. Proper process parameters for different raw water quality conditions can be determined by using the developed dynamic models, but the model parameters need to be adjusted.