Front. Environ. Sci. Engin. China 2007, 1(1): 57-62 DOI10.1007/s11783-007-0011-7 RESEARCH ARTICLE Classification of contaminants and treatability evaluation of domestic wastewater WANG Xiaochang(<), JIN Pengkang', ZHAO Hongmei, MENG Lingba I School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China 2 Beishiqiao Wastewater Purification Center, Xi'an 710003, China C Higher Education Press and Springer-Verlag 2007 Abstract Long-term sampling and analysis were conducted particle separation [4], utilization of inorganic coagulants in a domestic wastewater treatment plant for the investigation and polymers [5], post filtration [6], and post disinfection [7 on the characteristics of the representative contaminants inin the enhanced primary treatment process. Chemically raw sewage such as SS, COD, BODs, TP, and TN. All these enhanced primary treatment is also recommendable as the constituents were classified into dissolved and suspended first step of wastewater treatment prior to biological treatment groups by using a 0. 45-um membrane filter, and the concen- to achieve higher removal of organics and nutrients [8, 9 tration of each constituent in each group was analyzed. As a In general, organic and inorganic substances in the result, almost 100% of the Ss was found to be suspended domestic sewage may include both suspended and dissolved matter, as well as about 65% of COD, 60% of BOD,, 50% fractions, and the suspended fraction can be easily removed of P, and 20% of N. All these could be easily removed by by physical and/or physiochemical processes under most sedimentation or coagulation/sedimentation. A treatability conditions. However, some dissolved substances may attach evaluation diagram was proposed for a rational selection of on to the suspended particles. Therefore, as long as the suspen- wastewater treatment process in accordance with raw water ded particles can be effectively removed, the originall dissolved matter may also be removed substantially [1, 10 Regarding a selection of treatment technology, especially Keywords domestic wastewater, dissolved matter, sus- when primary or enhanced primary treatment is considered as pended matter, treatability evaluation the sole process for achieving certain water quality goals there is often a dispute on the evaluation of the treatment effect due to discrepancies of past experiences of different 1 Introduction people dealing with different wastewaters. The lack of a theo- retic base for contaminant classification and treatability eval- The contaminants in domestic sewage can be divided into uation has influenced a rational selection and optimization of three categories: suspended solids (SS),organic matter the wastewater treatment process [1l (chemical oxygen demand or biochemical oxygen demand), In this paper, the authors used the domestic sewage at and nutrients(nitrogen and phosphorus), which are the sub- the Beishiqiao Wastewater Purification Center, Xi'an,China stances to be removed by conventional and/or advanced treat- as an example, and through long-term water quality analysis ment for the purposes of discharge or treated water reuse. investigated the distribution of contaminants of different conventional treatment processes often consist of primary categories and different fractions. On this basis, a water treatment(physical process)and secondary treatment(bio- quality matrix was formulated and the treatability of con- logical process). In recent years, enhanced primary treatment taminants by primary, enhanced primary, and secondary that utilizes a chemical coagulant to assist the removal of sus- treatments was evaluated pended and dissolved contaminants, has drawn wide attention for wastewaters that are not amenable to conventional bio logical treatment[1], especially in developing countries [2, 3]. 2 Materials and methods Many studies have been conducted on the optimization of 2.1 Raw domestic sewage [译自:给水排水] Raw domestic sewage used for this study was from the inletFront. Environ. Sci. Engin. China 2007, 1(1): 57–62 DOI 10.1007/s11783-007-0011-7 RESEARCH ARTICLE Classification of contaminants and treatability evaluation of domestic wastewater WANG Xiaochang ( )1 , JIN Pengkang1 , ZHAO Hongmei1 , MENG Lingba2 1 School of Environmental and Municipal Engineering, Xi’an University of Architecture and Technology, Xi’an 710055, China 2 Beishiqiao Wastewater Purification Center, Xi’an 710003, China © Higher Education Press and Springer-Verlag 2007 Abstract Long-term sampling and analysis were conducted in a domestic wastewater treatment plant for the investigation on the characteristics of the representative contaminants in raw sewage such as SS, COD, BOD5, TP, and TN. All these constituents were classified into dissolved and suspended groups by using a 0.45-µm membrane filter, and the concen￾tration of each constituent in each group was analyzed. As a result, almost 100% of the SS was found to be suspended matter, as well as about 65% of COD, 60% of BOD5, 50% of P, and 20% of N. All these could be easily removed by sedimentation or coagulation/sedimentation. A treatability evaluation diagram was proposed for a rational selection of wastewater treatment process in accordance with raw water quality. Keywords domestic wastewater, dissolved matter, sus￾pended matter, treatability evaluation 1 Introduction The contaminants in domestic sewage can be divided into three categories: suspended solids (SS), organic matter (chemical oxygen demand or biochemical oxygen demand), and nutrients (nitrogen and phosphorus), which are the sub￾stances to be removed by conventional and/or advanced treat￾ment for the purposes of discharge or treated water reuse. A conventional treatment processes often consist of primary treatment (physical process) and secondary treatment (bio￾logical process). In recent years, enhanced primary treatment that utilizes a chemical coagulant to assist the removal of sus￾pended and dissolved contaminants, has drawn wide attention for wastewaters that are not amenable to conventional bio￾logical treatment [1], especially in developing countries [2,3]. Many studies have been conducted on the optimization of particle separation [4], utilization of inorganic coagulants and polymers [5], post filtration [6], and post disinfection [7] in the enhanced primary treatment process. Chemically enhanced primary treatment is also recommendable as the first step of wastewater treatment prior to biological treatment to achieve higher removal of organics and nutrients [8,9]. In general, organic and inorganic substances in the domestic sewage may include both suspended and dissolved fractions, and the suspended fraction can be easily removed by physical and/or physiochemical processes under most conditions. However, some dissolved substances may attach on to the suspended particles. Therefore, as long as the suspen￾ded particles can be effectively removed, the originally dissolved matter may also be removed substantially [1,10]. Regarding a selection of treatment technology, especially when primary or enhanced primary treatment is considered as the sole process for achieving certain water quality goals, there is often a dispute on the evaluation of the treatment effect due to discrepancies of past experiences of different people dealing with different wastewaters. The lack of a theo￾retic base for contaminant classification and treatability eval￾uation has influenced a rational selection and optimization of the wastewater treatment process [11]. In this paper, the authors used the domestic sewage at the Beishiqiao Wastewater Purification Center, Xi’an, China as an example, and through long-term water quality analysis, investigated the distribution of contaminants of different categories and different fractions. On this basis, a water quality matrix was formulated and the treatability of con￾taminants by primary, enhanced primary, and secondary treatments was evaluated. 2 Materials and methods 2.1 Raw domestic sewage Raw domestic sewage used for this study was from the inlet of the Beishiqiao Wastewater Purification Center, Xi’an, Translated from Water & Astewater Engineering, 2004, 30(9): 38–41 [译自: 给水排水] E-mail: xcwang@xauat.edu.cn