Research On Treatment Processes Of Severely Polluted Urban River Water And On The Effects Of Heavy Metals On The Treatment Efficiency

Slightly-polluted water of urban river was suitable for adopting bypass treatment or in-situ treatment. However, many urban rivers in China were severely polluted by wastewater due to the deficiencies of wastewater collection or controls of pollution sources, which were suitable for adopting interception and diversion treatment. The dissertation investigated the Buji River whose typical water quality delegated the common existed water quality of urban river in South China, which was appropriate for using interception and diversion treatment.The dissertation focused on the treatment of severely polluted urban river water by the process of Hybrid Actuation System (HYBAS). The process of HYBAS was investigated and improved, and the optimum process conditions were achieved. Further more, other treatment processes were also invested and compared each other in treatment efficiency.Effects of some heavy metals including Ni2+, Cd2+, Cr3+, Cu2+and Pb2+on the wastewater treatment of urban river were investigated via batch tests, and short-term threshold Values of these heavy metals were achieved, which were Ni2+ at 60mg/L, Cd2+ at 70mg/L, Cr3+ at 90mg/L, Cu2+at 90mg/L and Pb2+ at 80mg/L. When the dosaged of heavy metal was higher than its inhibitory concentration in the batch experiment, the removal of ammonia nitrogen and COD was obviously inhibited, and the ammonia nitrogen and COD concentrations couldn't decrease with time significantly in a short period of time. After the individual addition of shock load or continuously dosage of the inhibitory concentration of heavy metal into the continuously running reactor, the removal of TN and COD decreased at the beginning, but it could recover later. Besides, the effect of Ni2+ on the prior acclimated activated sludge to Ni2+ was also investigated, which mainly focused on its treatment performance.Variations of EPS content and EPS composition under the influence of some heavy metals were investigated. The investigation included shock load test and continuous dosage test. After the individual addition of shock load of some heavy metal including 60mg/L Ni2+,70mg/L Cd2+,90mg/L Cr3+,90mg/L Cu2+ and 80mg/L Pb2+, the EPS contents of both activated sludge and biofilm increased distinctly, and the more poisonous the heavy metal was, the more the EPS content increased. Then, the EPS contents gradually decreased with time, but it didn't meet the previous level without the addition of heavy metal even at the 530h after the heavy metal addition. The percentage of EPSs decreased quickly at the beginning, and it gradually stabilized with time. During this period, the more poisonous the heavy metal was, the more the percentage of EPSs decreased. Further more, the C/P of activated sludge and biofilm both decreaded queickly at the beginning, and it tended to stabilize with time. The result also indicated that the C/P of activated sludge decreased more quickly and more than that of biofilm, and it would be obvious when the heavy metal was more poisonous. After the continuous dosage of 60mg/L Ni2+ into the HYBAS reactor, the EPS contents of both activated sludge and biofilm increased at the beginning, then, they significantly decreased to a state in which the EPS contents were lower than those before the Ni2+ addition. Hereafter, both of their EPS content recovered when the bacteria gradually adapted to the influence of Ni2+. The EPSs and the EPSb of biofilm were influenced less than those of activated sludge, and were more liable to recover. When the EPSs of both biofilm and activated sludge stabilized, they both became a little smaller than those before the Ni2+ addition. The result also showed that the settleability of activated sludge was severely influenced by the EPS compositions and EPS contents.