UV Irradiation For Accelerated Biodegradation Of The Organic Matter

The internal-loop airlift reactor was combined the technology of photolysis andbiodegradation. The advantages of photolysis and biodegradation were taken well.Through photolysis, the toxicity of organic matter was reduced, while thebiodegradability was improved. This method of biodegradation had the advantages oflow cost and mineralization completely. Phenol and sulfamethoxazole was treated inthe reactor with the methods of photolysis alone (P), biodegradation alone (B) andintimately coupled photolysis with biodegradation (P&B). Then the degradation andmineralization of the two organic matters was researched. The microbial communitiesin the biofilm, being in the protocol B and protocol P&B, were analyzed by molecularbiology technique. The results indicated that protocol P&B has a very good effect onthe degradation of the two substances; the degradation and mineralization were boththe highest in the three protocols.During the degradation process of phenol, the degradation degree was relativelylow. But it was in line with the first-order kinetics. The removal rate decreased withthe increasing of the phenol initial concentration. For the initial concentration lessthan300mg/L, the removal rate increased with the increasing of the initial phenolconcentration by the protocol B, and it was higher than that by the protocol P&B. Onthe contrary, with the initial phenol concentration greater than300mg/L, the removalrate decreased with increasing of the initial phenol concentration by the protocol B, itwas lower than that by protocol P&B. It was found that SMX has a strong inhibitoryeffect on microbial in the degradation of SMX. The removal rate was low by theprotocol B. The removal rate was increased by the protocol P&B because UV candestroy the structure of SMX, and was much higher than that by protocol P andprotocol B. The influence of the initial SMX concentration was little to the initialSMX removal reaction rate by protocol P. The removal rate of TOC was highest bythe protocol P&B, which reached57.3%after6hours. While it was26%by protocolB and6.8%by protocol P.32.3%of nitrogen was released in the form of ammoniathrough the photolysis of SMX. The ammonia could be used as a nitrogen source for the growth of microbe. However, it could not meet the needs of the growth andmetabolism of microbe. Co-metabolism could form between the glucose and SMX.The energy could be provided to the degradation of SMX by metabolize of glucose.Then the biodegradation of SMX was promoted.The species and accounts of microbial community in the biofilm were studiedusing molecular biology technique. The results showed that, the strains ofBeijerinckia, Mesorhizobiun sp. Thauera sp. MZ1T and Ralstonia eutropha weredominant in the biofilm of biodegradation of phenol. Their proportion are26%，16%，16%å'Œ12%. However, by the protocol P&B, the proportion of strains Beijerinckia,Mesorhizobium sp. and Ralstonia eutropha dropped to4%,4%and6%because ofsensitive to ultraviolet light and the changed of substrate. While the Thauera sp.MZ1T became to the dominant strain, the proportion increased to40%. In thedegradation of SMX, The strains of Rhodopirellula baltica and Methylibiumpetroleiphilum PM1, dominated to the degradation of organic macromolecule matters,became to the dominant consortiums by protocol B, and the proportion got26%and14%. However by protocol P&B, the proportion of Rhodopirellula baltica andMethylibium petroleiphilum PM1reduced because of the changing of SMX structure,Rhodopirellula baltica was only7%, and Methylibium petroleiphilum PM1disappeared in the process of degradation. The strains of Micrococcus luteus, Delftiaacidovorans and Oligotropha carboxidovorans, dominant to the degradation of smallorganic molecules, became to the dominant strains by the protocol of the P&B, theirproportion are25%,19%and19%. The mineralization of SMX was improved greatlywith the role of other bacteria.In summary, the technology of photolysis and biodegradation were combinedwell in the method of intimately coupled photolysis with biodegradation (P&B). Theorganic matter could be degraded efficiently with this method. It was an effectiveprotocol to the removal of organic matter.