Study On The Degradation Of Glutaraldehyde By Microbial Method

Glutaraldehyde (GA) was widely used as biocides or crosslinking agents because of its two active aldehyde groups can react with ammonia or amines. While with the increasing use of GA, more and more people payed attention to the removal of GA from water because of its hazards and toxic effects. The traditional treatments were physical and chemical methods, degradation of GA with rotating biological was researched only by few people and the highest concentration of the degradation was only180mg/L without clear mechanism of degradation. This study acclimated the activated sludge collected from municipal sewage treatment plant to degrade GA and discovered the best conditions of the glutaraldehyde biodegradation (optimum pH, temperature, dissolved oxygen, initial concentration of glutaraldehyde, etc.). In addition, the effect of chemistry in the glutaraldehyde solution on the biodegradation of glutaraldehyde preliminary and the intermediates of degradation was explored and the best carrier and process were selected. The main results were as follws.(1) The activated sludge domesticated from different sources also can degraded glutaraldehyde. The degradation of the sludge from aeration tank of ordinary municipal wastewater treatment plant was pretty high, the daily degradation rate was beyond70%with initial concentration of glutaraldehyde2000mg/L(calculated with COD). Especially when the exchange of water is close to100%, it can up to80%.(2) Studies for characteristics on degradation showed that pH was important for glutaraldehyde degradation. The pH will decline to about4rapidly, followed by a slow rise with an ultimate degradation rate about85%, when the initial pH of7-8, and unadjusted it in the process; if we adjusted the pH in the degradation process to maintain pH7-8, glutaraldehyde degradation rate can reach more than90%. Besides, it was found that Glutaraldehyde degrading bacteria were very sensitive to temperature, the degradation rate increased with increasing of temperature, but its ultimate degradation rate cann’t change.Especially, the degradation was paused almost when the temperature dropped to10℃. At the same time we discovered,dissolved oxygen(DO) has little effect on glutaraldehyde degradation when DO was sufficient, while the rate of degradation is reduced, but DO didn’t affect the final degradation level of glutaraldehyde. Moreover, the degradation can be seen as a linear procedure when glutaraldehyde’s initial concentration was500mg/L or less; when initial concentration was700mg/L, the degradation of the initial was blocked; the block will be stronger when the incipient concentration up to900-1000mg/L; the initial block time up to16h when the initial concentration to1200mg/L inhibition of degradation. Furthermore, Adding a simple carbon source in high concentrations of glutaraldehyde didn’t eliminate the block, and the degradation of a simple carbon source was inhibited by glutaraldehyde. Finally, it was showed that the greater the amount of bacteria of domesticated bacteria inoculated, the shorter the time was desired by degradation of glutaraldehyde.but the inoculation amount didn’t change the final degradation rate of glutaraldehyde, also.(3) There was a equilibrium between glutaraldehyde and its hydrates in Glutaralde-hyde’s aqueous solution, and the glutaraldehyde molecules can polymerized with the product was different under acidic conditions and alkaline conditions.Besides, the polymerization was faster in the strong alkaline conditions, and the product will generated absorption peak at233nm; more importantly, glutaraldehyde reacted with ammonia in a strongly alkaline conditions quickly, generated the white powdery substance and yellow substance. These substance can’t be decomposed by microbe domesticated; the degradation rate of glutaraldehyde. nitrogen injected was more than50%higher than the no nitrogen. What’s worse, the domestication was invalid to microorganisms under condition of no nitrogen; the nitrogen consumption in30h was determined in degrading of GA was about13mg/L; Increasing in ammonia concentration had little effect on the degradation of GA. What indicated that the nitrogen promoted degradation of GA through improving the microbial activity, mainly. glutaraldehyde degradation intermediates will most probably glutaric acid.The experience for biofilm building showed that it was benefit on biofilm building to increase the amount of aeration.compared5carriers to find the fastest of biofilm builded and stablest carrier for biofilm and degradation. The system builded by suspended particles packing had the stablest biofilm and degradation of GA.the adsorbability of Biological rope packing was so strong that they adsorbed too much productions reacted by GA and ammonia to degraded GA high-efficiency. Compare glutaraldehyde degradation of activated sludge method with biofilm process which the biofilm was builded by the carrier which had the faster builded, gained that activated sludge process is more resist on shock...