| Organophosphorus pesticides(Ops) are major pesticide agents around the world.The low toxic Ops have their advantages make good and effective control to vegetable pests. However as a result of long-term OPs using, it brought some bad consequences such as strong resistant, excessive OPs residue and so on. This research is intended to find an effective, economic and simple method to deal with the serious pollution of OPs. We proposed to use the anaerobic digestion(AD)system to make the OPs degrade under the temperature conditions of 30 ℃.Moreover,we can get a kind of green energy biogas at the same time during the whole OPs degradation process.We use enzyme inhibition spectrophotometry method(EIM) to detect the concentration of OPs in the bio-slurry. It is shown that the threshold of degradation for the AD system is 160mgL-1. All the systems which having OPs(Dimethoate) in them got the different degradation fastigiums with different degradation rates respectively. 10-50 mg L-1: the 3rd day, 93.2%, 75.5%, 73%, 77.6%, 81%; 60-90mgL-1: the 4rd day, 82.7%, 82.9%, 77.1%, 77.6%; 100-120 mg L-1: the 6rd day,89.1%, 83.7%, 78.3%; 130-160 mg L-1: 7rd day, 78.1%, 69.2%, 52.9%, 50.3%. The higher concentration of OPs the system has, the longer degradation period it will get. We used the math software Matlab 7.0 to fit the process of degradation with Rayleigh model, it turned out that every correlation coefficient is greater than 0.99.As to the cumulative biogas production, the concentration of OPs has marked effect on it. Its yield decrease along with the promotion of the OPs concentration.The cumulative biogas procedures in all the systems abide first-order kinetics.Their fitting correlations R2 s of the modified Gompterz model are greater than0.993. The OPs will also have negative effect on the daily biogas production when their concentrations rise to 80 mgL-1. The yield of daily biogas production and its peak time of control group and experiment group are shown: 220 mL, the 8rd day;240 mL, the 8rd day; 230 mL, the 9rd day; 300 mL, the 8rd day; 300 mL, the 11 rd day, … … 140 mL, the 23 rd day, 90 mL, the 20 rd day. We detected the methane concentration in the experimental period. And we found that the average methane concentration of the control group which did not add OPs is 65.2% and the other group which added dimethoate is respectively: 62.7%, 60.3%, 61.5%, 62.2%...56.7%, 52.4%, 50.1%. The data of average methane concentration shown that when the initial concentration of the concentration of dimethoate over 80 mg/L(56mg) can lead to significantly decrease of methane content. At the same time, the addition of organophosphorus pesticide dimethoate made fermentation liquid become acidic. With the dimethoate degrading, the pH value of anaerobic digestion system returned to normal. In the anaerobic digestion process, the pH value of degstion liquid always stays between 6.2 and 7.4.Anaerobic digestion system can effectively degrade OPs, dimethoate. It can convert waste vegetable to energy during degrading process of OPs. It is a practical method which is feasible to promote and can solve the problem of organicphosphorus pollution and pesticide residues. |
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