| With the technological and economic development, there are lots of new synthetic chemicals to serve the people more better everyday. People become more concern about the harm of these new chemicals to the environment and humans. Biodegradation is an important way to removal of chemicals in the environment. In order to measure their fate in the environment to migrate by biodegradation test of these compounds. Rapid biodegradation test (RBT)(OECD301series) is the most prominent biodegradation screening test performance using a set of international biodegradability testing. All new chemical substances must provid RBT these results to determine whether chemicals has rapid biodegradability. However, during the test, we found that rapid biodegradation test the poor reproducibility and comparability. The innoculum biological activities may directly influent the results.In this study, according to the Organization for Economic Cooperation and Development (OECD) guidelines for testing of chemicals specified and domestic "chemical test methods" ready biodegradation test301F. Firstly, different sources of activated sludge were collected and pre-conditionning. And its biological activities were assayed during this process and found the relationshion between the pre-conditionning time and its biological activities. Secondly, different sources of activated sludge were collectied and analysised their biological activities. Further more, these activated sludge as inoculum to RBT of four chemicals, such as, sodium benzoate, p-nitrophenol, acetaminophen, diclofenac sodium. The relationship between the biological activities and RBT results was found out.These results showed that the biological activities of different sources of sludge, such as hydrolysis activity, dehydrogenase activity (DHA), ATP content, Oxygen taken rate (OUR) they have consistent trends with pre-conditionning time. Hydrolase activity reached its maximum in5-7days and it shows that preconditioning was of benefits for improving of hydrolase activity in activated sludge. DHA could be maintained at a stable level during3days to7days and then declined significantly after7days. OURn and ATP content was reduced with the extension of pre-adjustment time. Due to the biodegradation capacity of active sludge became decline with the extension of time to preconditioning. DHA, OURN and ATP content may have some impact on the degradation of activated sludge because of their trends. And hydrolysis activity may not influence the biodegration.A comprehensive evaluation of the activity of activated sludge for measurement their degradation capacity is more comprehensive. There are a certain relationship between the lag time of RBT and the biological activity in RBT of p-nitrophenol. The results shows that biological had little impact on the results of RBT of sodium benzoate, acetaminophen, diclofenac sodium biodegradablility. The comprehensive biological activity index of A, B, C Sludge was8,7,11and greater than5, but D sludge only got4. According to the dynamics of nitrophenol degradation curve p-nitrophenol, the sludge A, B, C lag period were4days,2days and2days. A, B, C can be reached by the pass level after6days. Integrated biological activaties of A, B, C were higher than D, so the lag period is shorter than the curve in the D sludge. When integrated activity index too low, lag period will be affected obviously. D lag period was7days, which was less than the rest3kinds of activated sludge. D sludge needed longer time than other sludges to achieve the pass level. A, B, C sludge have no significant difference between the lag period time and they reached the pass level in6days because their comprehensive activity index were higher. The nitrophenol degradation ability in A, B, C sludge were relatively close and unable to distinguish, so a lot of RBT for kinds of compounds were needed. |
PDF Full Text Request