Study On Design And Commissioning Of Kitchen Waste Treatment Project

As a kind of food waste produced by people in daily life,kitchen waste is featured by high content of water,organics and salt,which will significantly harm people’s living environment and physical health if it is improperly treated.Currently,kitchen waste is treated through landfill,incineration,anaerobic fermentation,compost and other methods abroad,of which anaerobic fermentation is widely used owing to its advantages such as mature and reliable technology,thorough harmlessness and high recycling.Moreover,anaerobic fermentation is regarded as the direction where kitchen waste treatment technology will develop.In addition,the composition and characteristics of kitchen waste in China are very different from those in foreign countries,so the pretreatment of kitchen waste is also critical.Taking Shijiazhuang as an example,this paper analyzes the composition and physical and chemical properties of kitchen waste in this city.According to the analysis results,relevant experiments are conducted on the kitchen waste samples to demonstrate the effect of anaerobic fermentation on the kitchen waste treatment,and high-temperature hydrothermal degradation is also adopted to pretreat the kitchen waste.Based on the forecast of the daily waste volume generated in the urban area,the capacity of the kitchen waste treatment plant is determined as 300t·d^-1.After determining the main treatment technology and processing capacity,this paper designs a kitchen waste treatment plant.The treatment process used is“waste collection and transportation-pretreatment-anaerobic fermentation-composting with biogas residue-biogas power generation”.The process of“sorting-high-temperature hydrothermal degradation-two levels of squeezing-centrifugation and oil extraction”is selected for the pretreatment system,which can realize impurity removal,crushing and oil extraction of kitchen waste.After pretreatment,the kitchen waste enter the anaerobic fermentation system.After selection,analysis and process calculation,finally,the form of anaerobic reactor selection is Type CSTR Reactor,whose volumetric load is 3.6 kgTS·（m³·d）^-1.By calculation,the tank capacity of 10410 m³ is required.Actually 2 fermentation tanks with the capacity of 5300 m³ each are selected.The dwell time of the total water power is 29.4days.The biogas generated by anaerobic fermentation entered the generator for power generation after desulfuration.After anaerobic fermentation,solid-liquid separation is completed for the fermentation broth,the biogas residue enter the composting system,and the biogas slurry enter the sewage disposal system for treatment.This process has features such as high treatment efficiency,high resource conversion rate,easy operation and stable operation.Reduction and recycling treatment can be made harmless for kitchen waste.The material balance during the processing of each unit is calculated,and the equipment model is selected for the major processing units.The kitchen waste is converted into gas,electric energy,organic fertilizer and other recycled products after treatment,and the sewage is treated and discharged after meeting the standard,which realizes harmless,reducing and recycling treatment.The core unit of this design is pretreatment and anaerobic fermentation.Their debugging is very important.This paper analyzes the debugging process of the pretreatment and anaerobic fermentation system,mainly including equipment debugging,debugging with material and sludge seeding.By debugging,the system can operate with the design indexes.The parameter control in the process of debugging is analyzed.After commissioning,the kitchen waste treatment plant enter the normal operation stage.After a period of operation,the collection and transportation capacity are gradually stabilized and reached 91.4%of the design value,with an average unit gas production of85.74m³·t^-11 and an average oil extraction rate of above 5%,showing stable output.It can be seen through analyzing the changes in the relationship between the feed volume and the unit gas production that the processing efficiency of the anaerobic fermentation system is closely related to the stability of feed volume.The plant designed is to process 300t·d^-1 of kitchen waste,with a floor area of about80 mu and a total estimated investment of RMB 208.8208 million.The analysis of the plant’s production costs,revenue estimates,profitability,sensitivity,and breakeven indicate that the construction of this plant is both environmentally and socially profitable.This design study can provide a meaningful example and reference for the design of kitchen waste treatment plants in other cities.