Research On Application Of Microwave Assisted Sulfate Radical In Sludge Treatment

With the urbanization process is accelerating in our country, urban sewage treatment plant rate showed a rising trend, urban sewage treatment plant sludge production also increased dramatically. Improper disposal of sludge into the environment, would pose a serious threat to Ecological environment and human activities. Particularly in high level of urbanization cities and regions, the sludge outlet problem has become increasingly prominent. Sludge is formed by a variety of microorganisms zoogloea aggregates, containing a large recalcitrant organics, highly perishable. Over the years, people have been seeking a way for excess sludge reduction and stabilization, anaerobic digestion is often used. Anaerobic digestion of sludge disposal is low energy consumption, high stability, and can produce methane and other available resources. However, anaerobic digestion reaction rate is slow, high demand for external conditions. Hydrolysis stage is restrictive phase in anaerobic digestion. Microbes are major components of the sludge, the matrix contained within the cell membrane allows the anaerobic fermentation, but the rigid structure of the cell wall membrane would obstacle and shield the substances which are easily degradable. Take a series of methods of sludge pretreatment, the purpose is to destroy the cell wall membrane, release intracellular substances to enhance the biodegradability of sludge to improve the rate of hydrolysis.Potassium persulfate due to its strong oxidation、high stability at room temperature、 water solubility、relatively low prices, etc to get a lot of attention. But only rely on persulfate oxidation degradation of organic matter is difficult to achieve the desired results, you need to stimulate their produce sulfate radicals to degrade organic matter. In this paper, microwave-assisted sulfate radical methods of sludge treatment, by changing the dosage of potassium persulfate, microwave power, time, examine its impact on the nature of the remaining sludge, analysis the parameters trends of treated sludge in order to determine the optimal pretreatment dosage of potassium persulfate, the best microwave power, the best microwave time; thus sludge anaerobic digestion will carry on, analysis of gas production and crack sludge supernatant VFA, total alkalinity, SCOD, TN, TP, pH and other parameters trends in sludge anaerobic digestion process, examines the pretreatment on the impact of anaerobic digestion.The results showed that under the conditions of the microwave adding potassium persulfate, can be more quickly and efficiently produce such that persulfate sulfate radical (SO4-·), to enhance its oxidative capacity and destruction of microbial cells in the sludge structure more fully, accelerate the sludge break. When K2S2O8dosage0.3g/gSS, microwave time was120s,400W microwave power, the sludge removal rate reached17.9%. Under the effect of oxidants, the sludge microbial cells are destroyed, some intracellular organic matters are released to the sludge supernatant, the processing of SCOD increased from226mg/L to796mg/L, the TN increased60.2%than before treatment; Intracellular substances released into the sludge solution, the concentration of protein increased from26.3mg/L to58.6mg/L, the polysaccharide concentration increased from13.7mg/L to44.1mg/L.In the process of anaerobic digestion, pretreated sludge than the average daily production of raw sludge increased by35.8%, and gas production peak ahead of the2d; Preconditioning not only improves the performance of anaerobic digestion, but also shorten the residence time of sludge. Not be pretreated sludge and pretreated sludge anaerobic digestion of TP showed a clear upward trend. After pretreatment the sludge increased from the beginning of the reaction38mg/L to64mg/L, increased by68%. Anaerobic digestion process is divided into acidogenic and methanogenic phase, reaction initial stage pH showed decreases firstly and then increases, total alkalinity also changed.