The Study On The Treatment Of Reservoir Water Derived From Yellow River By The Technology Of Gac-sand Filter

This study is the sub-topics of "The Research and Demonstration of Strengthening Conventional Process Integration Technology to treat the Yellow River Reservoir Water with High Algae", which is the third of "The Research and Demonstration of the Drinking Water security technology in the Lower Reaches of Yellow River lower". It belongs to "The Research and Demonstration of the Drinking Water security technology" which is from Major science and technology program named "State Water Pollution Control and Governance".Aim at deterioration of water quality, such as the high content of nitrogen and phosphorus nutrients and algae pollution characteristics, the waterworks transformed a group of sand filter into GAC-sand filter, in order to meet the requirements of the new water quality of drinking water health standard (GB5749-2006).The main contents of the study include three aspects:(1) Comparing the purification effect of GAC-sand filter and sand filter through experiment;(2) To determine the backwash cycle of the GAC-sand filter according to the filter head loss and turbidity;(3) The regeneration of activated carbon is discussed in the end of the article.By comparing the water quality of GAC-sand filter and sand filter, it is found that the removal efficiency of GAC-sand filter on turbidity, CODMn, TOC, UV254and ammonia nitrogen are much better than the sand filter. In the GAC-sand filter, the average removal rates of CODMn, TOC, UV254and ammonia nitrogen are38.92%,50.42%,61.04%and44.33%, respectively. In the sand filter, the average removal rates of CODMn, TOC, UV254and ammonia nitrogen are10.23%,7.95%,8.26%and30.24%, respectively. During the test, the number of raw water algae is up to109orders of magnitude. The number of Algae is at a high level, reaching the state of eutrophication. After treatment, the alga of raw water has drastically reduced. Most of the algae are removed by flotation, however, filtration unit on removal of algae have some effect, and in the GAC-sand filter the number of algae is slightly less than the sand filter.After the examination, it is found that the odor substance of the raw water is relatively large. MIB and GSM of raw water are74.81ng/L and4.29ng/L, respectively. Traditional process is extremely limited to the removal of GSM and MIB. However, activated carbon can be an effective adsorption of GSM and MIB, and its removal rates are higher than the sand filter. In the GAC-sand filter, removal rates of MIB and GSM are up to89.28%and93.43%, respectively.According to the study on the removal of disinfection by-product precursor, it is found that traditional process is limited on removal of disinfection by-product precursors, the GAC-sand filter can effectively adsorb disinfection by-product precursors, its removal rates is higher than sand filter.During the test, in the GAC-sand filter, the pH of inlet and outlet are above7.5, which make for the microbial nitrification, reduce the ammonia nitrogen of water and improve water quality.The test takes the head loss and turbidity as control indexes, optimizes backwash cycle of GAC-sand filter. Considered from the perspective of head loss, the backwash cycle of GAC-sand filter is5-6days. Considered from the perspective of turbidity, the backwash cycle of GAC-sand filter is3-3.5days. After comprehensive consideration of the relationship between the filtration cycle and the two indicators, the final decision is that filtration cycle of GAC-sand filter is3days which determined by turbidity.From actual operating results of Xin’an water plants, GAC-sand filter can improve water quality of water supply plant, and it does not add infrastructure investment. GAC-sand filter has the advantage of running a safe, convenient and effective, which adapt to the water treatment plant upgrade, and demonstration of significance. Finally, article briefly describes the necessity and method of regeneration of activated carbon, and compares the conditions of application, advantages and disadvantages of the various regeneration modes. The regeneration of "saturated carbon" has an extremely important value in engineering and economic.