The Experimental Study Of Hydrolytic Acidification-Anoxic-Aerobic Process On The Treatment Of Petrochemical Wastewater

The petrochemical wastewater has the characteristics of high orgainics concentration, complex pollutants composition and poor biodegradability. The treatment of petrochemical wastewater is the focus in the field of wastewater treatement technology. In this study, a large-scale integrated petrochemical wastewater treatment plant was referred as the research object to build a laboratory-scale experimental equipment. The optimization of the operation parameters of the hydrolysis-acidification-anoxic-aerobic process was investigated using this equipment. In addition, the enhancement of the hydrolysis-acidification unit, and the dissolved organics in the effluent was also measured and analyzed during the operation. The purpose of this study was to provide support for sewage plant process innovation, and to provide the reference for research of intensive the hydrolysis-acidification technology and the hydrolysis-acidification-anoxic-aerobic process.The results showed the best operating parameters are as follows:the sludge recycle ratio (R)100%, the hydraulic retention time (HRT) of the aeration tank15h, the DO2-3mg/L, and the sludge age17～24d. At that condition, the effluent COD was the lowest and the COD removal rate was the highest, which were62.5mg/L and88%, respectively.Optimizating and improving hydrolysis acidification showed that the optimal hydraulic retention time (HRT) for hydrolysis acidification unit was14h, and the optimal proportion for industrial wastewater and domestic sewage was1:1. When appling this condition, the biodegradability of the wastewater was the best, the COD was the lowest and lowest and the UV254was the minimum. Adding the filler to hydrolyze acidification unit let COD removal rate increasing by50%. Improving and optimizing hydrolysis acidification unit made the effluent biodegradability increased98%than thaf of influent Increasing micro aerobic that could enhance the mixing to the hydrolysis acidification pool did not destruct the reduction environment. Therefore, it had little effect on hydrolysis acidification of macromolecular substances in wastewater.The classification and analysis of effluent of hydrolysis acidification unit showed that small molecule soluble organic matters with molecular weight lower than1000were the highest proportion in both of improved hydrolysis acidification and sewage treatment plant hydrolysis acidification tank, which were86%and54%, respectively. Three-dimensional fluorescence spectra show that the the effluent organic matter is mainly tryptophan protein aromatic species. Dissolved organic matter (DOM) in a biological effluent collected from a typical petrochemical wastewater treatment plant was isolated and fractionated using resin adsorption method. The fractions were operationally categorized as hydrophilic substances, hydrophobic acids, hydrophobic neutrals, and hydrophobic bases. Hydrophilic substances and hydrophobic acids are the main type of DOMs in the effluent, which accouting about49%and29%of the TOC, respectively. The peaks of infra-red spectrum of the4fractions mainly distributed in the district of600cm-1-1200cm-1, indicating that similar compounds of balmy isomers exist in the wastewater samples.Qualitative analysis of organic matters in the wastewater was carried out by GC-MS. The analysis showed that there were lots of benzenes and hydrocarbons in sewage plant hydrolysis acidification-anaerobic-aerobic tank effluent. These organics can be removed greatly by enhanced hydrolysis acidification in the laboratory-scale experimental process, which reduced the stress of the following anoxic-aerobic process.