Study Of Urban Night Soil Treatment Process Selection

With the accelerated urbanization process, urban population has increased and concentrated, making the city increased night soil output. Night soil for agricultural fertilizer in rural areas and urban infrastructure, blocked the construction lag,and the night soil is not timely and effective treated, resulting in a certain environmental pollution, influencing and even threating the lives and health of residents, which focused on urban wastes and treatment processes Methods facilities is urgent.This data is based on the urban population nearly years, through the establishment of Grey Model - GM (l, 1) model to predict the urban population and the capacity of feces. Night soil treatment process for the selection of city machinery exists to apply the phenomenon of the city of several commonly used manure treatment process, and the impact of night soil treatment process factors affecting the choice of depth and detailed analysis, and through the establishment of evaluation index system, the use of AHP France to focus on the impact of process selection stool comprehensive comparison of factors, through case analysis, the following conclusions:1. City focus on process selection feces affected by many factors, technical properties:organic matter removal, process maturity; economic benefits: investment, energy consumption, drug consumption, covering; operation management: process complexity, management ease of maintenance, process equipment stability. Among them, the removal rate and the acceptance of feces the size of the sewage treatment plant to deal with water quality is directly related to temperature and weather conditions, the relevant provisions of urban planning, capital and operating costs and other factors directly affect the selection process:⑴Municipal sanitation facilities in more complete and medium-sized cities should "Pretreatment Wastewater Treatment Plant", will be incorporated into the municipal wastewater treatment plant effluent fecal dilution, and for biochemical treatment of domestic sewage, fecal residue into the landfill after dewatering disposal both effective use of existing municipal sanitation facilities, but also save the costs, the operation of sewage treatment plants have a positive impact.⑵Mainly industrial waste water sewage treatment plant can not be entirely fluid filtration into the sewage containing feces, or load is too low, biochemical system unsustainable, therefore emissions from the energy point of view, and mainly to industrial waste water sewage plant matched field night soil with primary focus on treatment process, the filtration medium has basically met the maintenance of sewage plant wastewater system operation, so that the primary treatment process more reasonable, and feces should focus on supporting the construction site sewage treatment plant in the industrial zone.⑶To the main sewage treatment plant influent wastewater COD and BOD5 values in the already relatively high, the basic biochemical treatment to meet the requirements from time to enter the fluid filtration of sewage containing feces, thus supporting the main sewage treatment sewage plant, the city should dispose of manure treatment process using two⑷Stool scale centralized treatment plants is subject to its accompanying scale wastewater treatment plant. Large-scale sewage treatment plant can accept a large concentration of urban excreta disposal of manure liquid filtration, small-scale sewage treatment plant can not accommodate large-scale centralized filtration liquid manure⑸Frozen winter in the northern city of long, outdoor temperature is below 0℃, the arrival of night soil collection vehicle for the frozen state of stool, easy to damage the dewatering, composting and anaerobic digestion of high-temperature insulation and heating costs are high; the production of fertilizer neither northern winter sales, but also the storage, so influenced by the temperature of high temperature composting and anaerobic digestion, manure treatment process not the average temperature is lower in the northern city applied.⑹Night soil treatment process is also affected by urban town planning constraints, capital and operating costs and emissions limits required by the manager of the factors affecting the quality of high and low, in the choice of treatment process must be considered.2. Hefei manure treatment process to determineBy analyzing the technical performance, cost, operation and management evaluation factor 9 Construction of manure treatment technology evaluation index system, will rely on the night soil of urban sewage treatment plant primary treatment process, secondary and tertiary treatment process as the primary independent biochemical process program by constructing a comparison matrix to calculate the weight, eventually relying on secondary treatment of sewage treatment plants process the biggest weight, was chosen technology harmless treatment Hefei night soil.