| While raising animals,the farm produces a large amount of livestock manure and sewage,which has caused certain pollution to the environment.Therefore,in order to deal with the manure accumulation and resource utilization of pig farms in a timely manner,after the deep dehydration pretreatment based on spiral extrusion-electric osmosis-flocculation conditioning,the ultrafiltration-electrodialysis-reverse osmosis membrane combination process is used to comprehensively treat the separated pig wastewater to meet the discharge standards.The main research contents of this paper are as follows:1)Using the solid-liquid separation technology and treatment process combining electric osmosis,flocculation conditioning and mechanical pressing,the self-made electric osmosis dehydration experimental device conducted a deep dehydration study on pig manure,and explored the effects of different flocculants(polypropionamide,aluminum sulfate,polyaluminum chloride),mechanical pressure and voltage gradients on the dehydration efficiency of manure in pig farms.The experimental results show that the flocculation and dehydration effect of polyaluminum chloride is the best,and the dosage is 40mg/g DS;under the condition of mechanical pressure of 500 KPa and dehydration time of 30 min,the dehydration experiment of electric osmosis alone can reduce the fecal moisture content by 5%-8%,and the co-experiment of electropenetry and PAC flocculant can reduce the fecal moisture content by 10%-12%,and the dehydration efficiency is best when the electric field strength is25 V.The optimal operating conditions obtained by the small test platform test provide theoretical design parameters for the deep dewatering equipment.2)For the structural design of the deep dehydration equipment,the variable pitch spiral dehydration method is selected,the feces can be squeezed and dehydrated,and the moisture content of the manure can be reduced to 52% when the spiral compression outlet pressure is set to 0.5MPa;the internal flow field numerical simulation of the spiral extrusion area is carried out by different speeds(20,30,40r/min),and the optimal speed of the spiral strand is30r/min,and the efficiency of solid-liquid separation can reach about 50%,which further verifies the dehydration performance of the equipment.The design idea and speed selection of spiral stranded dragon provide a theoretical basis for the production and manufacture of subsequent deep dehydration equipment.3)A small-scale test platform for harmless treatment of pig farm wastewater with ultrafiltration electrodialysis reverse osmosis technology as the core has been designed and built by ourselves.Through experimental analysis and selection and optimization of its operating conditions and parameters,the separated water can meet the water quality standard for farmland irrigation(GB5084-2005)and solve the problem of pig farm manure treatment below the scale.Finally,the ultrafiltration feed water pressure of 0.25 MPa,electrodialysis voltage of 3V,and reverse osmosis feed water pressure of 0.55 MPa are selected for the best efficiency of treating wastewater.The optimal operating parameters obtained after treating wastewater through the pilot platform provide a theoretical basis for the design of subsequent membrane process wastewater treatment equipment. |
