Research On Kitchen Wastes Anerobic Digested Effluent Process By Chlorella

Nowadays, anaerobic digestion technology was usually applied in kitchen wastesprocessing, but the process of anaerobic digested effluent produced in the kitchenwastes disposal was less researched. This paper succeeded in applying chlorella toprocess kitchen wastes anaerobic digested effluent, made the most contaminants in thekitchen wastes anaerobic digested effluent remove, kept chlorella grow well in thekitchen wastes anaerobic digested effluent, completed the resource utilize of kitchenwastes anaerobic digested effluent. The anaerobic digested effluent was preprocessed atthe beginning, cultivated chlorella in a heterotrophic way, then the influence of factorson anaerobic digestion liquid processing by chlorella was studied. Firstly,orthogonalexperiment was designed to explore the influence of chlorella inoculation quantity, pH,temperature, digestive juice concentration and C/N on contaminants removal in kitchenwastes anaerobic digestive juices. COD, total nitrogen, ammonia nitrogen and totalphosphorus were considered as pollutants indexes mainly. Five factors’ impact onchlorella biomass was also analyzed. Secondly, control conditions of kitchen wastesanaerobic digestion liquid degradation by chlorella were optimized through the responsesurface optimization. Built quadric surface equations of COD removal rate, totalnitrogen removal rate, ammonia nitrogen removal rate, total phosphorus removal rateand chlorella biomass. Identified optimal control conditions of the five indicators andtotal optimal control conditions. Finally, made a principal component analysis for fiveindexes in the control condition optimization phase, established two principalcomponents and a comprehensive evaluation function, carried on comprehensive scorefor the test results in response surface optimization. According to the tests and analysis,obtained the conclusions:（1）In the process of kitchen wastes anaerobic digestion liquid degradation bychlorella, chlorella inoculation quantity, pH, temperature, C/N and digestive juiceconcentration, the five factors’ order of influence on COD, total nitrogen, ammonianitrogen, total phosphorus removal rate were temperature>inoculation quantity>digestive juice concentration>pH>C/N, temperature>digestive juice concentration>pH>C/N>inoculation quantity, temperature>digestive juice concentration>inoculationquantity>pH>C/N,temperature>inoculation quantity>pH>digestive juice concentration>C/N, respectively. The influence order of chlorella biomass was temperature>digestive juice concentration>chlorella inoculation quantity>C/N>pH.（2）In the optimizing experiment for control conditions, established quadraticresponse surface equations for COD removal rate, total nitrogen removal rate, ammonianitrogen removal rate, total phosphorus removal rate and chlorella OD₅₁₇.Interactions ofchlorella inoculation quantity and digestive juice concentration made a bigger influenceon the removal rate of COD, ammonia nitrogen and total phosphorus.Interactions ofthree factors rarely made influences on total nitrogen removal rate and chlorellabiomass. According to the optimization calculation, the optimal removal rate of COD,total nitrogen,ammonia nitrogen and total phosphorus were97.76%,92.15%,95.27%and97.81%respectively.The optimal chlorella OD₅₁₇was2.04, equaled to the chlorelladry weight at1.021g/L.（3）Two principal components were identified through the principal componentanalysis, established principal component functions for Z₁, Z₂. For principal componentZ₁, the COD removal rate, total nitrogen removal rate, and chlorella OD₅₁₇made agreater influence in five indexes.For principal component Z₂, the ammonia nitrogenremoval rate and total phosphorus removal rate made a greater influence. According tothe comprehensive appraisal made for the test results in the control conditionoptimization phase, the test conditions with high score in comprehensive evaluation wassimilar to the total optimal condition through the response surface optimization.（4）Combined with controlled conditions’ influence on the kitchen wastesanerobic digestion effluent treatment by chlorella and optimization experimental results,concluded total optimal condition for five indicators when the chlorella inoculationquantity at15.74%, pH at7.19, temperature at35℃, C/N at25, digestive juiceconcentration at40.58%. Under the condition, the comprehensive score of test resultwas1.419, the removal rate of COD, total nitrogen, ammonia nitrogen and totalphosphorus reached at97.47%,90.70%,91.62%and95.36%, respectively. ChlorellaOD₅₁₇arrived as2.03, equaled to chlorella dry weight at1.016g/L.