Biological Treatment Of Contaminated Water

Water is in great need of with the rapid development of industry and agriculture, the fast growth of population and the continuous growth of urbanization. So large amount of waste water is produced and released to oceans and lakes. Water pollutions are becoming worse and worse. Water remediation is created for the decrease of water quality and the failure of water quality improvement by pollutant source control.As a new, cheap and ecological sound technology, biological treatment of contaminated water system attract many scientists all over the world .The objectives of this study were: to analyze the factors causing contamination in Xinyi River of Huaihe River catchment, investigate on the strategies for controlling and remediating water pollution in Xinyi River, compare the effectiveness of ecological floating islands, immobilized nitrogen cycling bacteria (INCB) and zoobenthos on purifying contaminated water. The materials used included: Alternanthera philoxeroides, Hydrocharis dubia, artificial fillers, immobilized nitrogen cycling bacteria (INCB) and Bellamya aeruginosa. The main results obtained are summarized as follows:1. In the field experiments, it is actable and effective that purifying contaminated Xinyi River with ecological floating islands from Oct 20, 2002 to Nov 20, 2002. The average removal rates of COD_Cr, TN, NH⁺₄-N and TP were 19.6%, 8.9%, 25.3% and 13.8%, respectively.2. Before temperature decreased, ecological floating islands-microorganism performed well on purifying contaminated water and the best removal rates of COD_Mn, TN, NH⁺₄-N and TP were 50.2%, 29.8%, 49.3% and 57.9%, respectively. In low temperature season, the effectiveness of it dropped sharply, and the least removal rates of COD_Mn, TN, NH⁺₄-N and TP were 7.4%, 0.6%, 1.51% and 4.2%, respectively. It is showed that phytoremediation is limited on remediating contaminated water in fall and winter.3. In the conditions of lower temperature, it is stable and effective that purifying contaminated Xinyi River with INCB-microorganism. The removal rates of COD_Mn TN, NK⁺₄-N and TP maintained more stable compared with these of ecological floating islands-microorganism, and they were averagely 31.9%, 21.3%, 23.3% and 21.3%.4. In fall and winter, it could be solved in some extent by using ecological floating islands-microorganism combined with INCB-microorganism that the unsatisfactory effectiveness of phytoremediation on remediating contaminated water occurs whentemperature is getting lower and lower.5. In the lab experiments, zoobenthos, such as Bellamy a aeruginosa, showed effective ability in decreasing aquatic plants (e.g. Eichhornia crassipes) residues. The ultimate removal rate of SS (Suspended Solid) of the control was 8.9%. The ultimate removal rates of SS of Bellamy a aeruginosa, which were stocked in 3 densities: 30 individuals per tank, 60 individuals per tank and 90 individuals per tank, were 19.2%, 26.9% and 28.2%, respectively. It is showed that it could relive the secondary pollution caused by Eichhornia crassipes decomposing by stocking Bellamya aeruginosa.