Treatment Of Citrus Processing Wastewater Using Chemical Precipitation And Biodegradation With Penicillium Simplicissimum

Wastewater from the citrus processing industry contains large amounts of acid,peel, pulp, sugar, pectin and so on. It is characterized with complex composition, highconcentrations of pectins, large discharge capacity and unstable water quality. Besidesthe wasterwater is one kind of the most difficult to treat among the fruit and vegetableproduction wastewater. The traditional biochemical process is difficult to meet theneeds of actual citrus production wastewater treatment. Therefore to develop moreeffective technology of citrus processing wastewater treatment has very importantsignificance.This paper mainly studied the two processes for treatment of citrus processingwastewater. The first method is to use acid extraction and separation by salting-out toextract pectin from citrus processing wastewater; and the second method is usingPenicillium simplicissimum CGMCC3.3241for pectin degradation from citrusprocessing wastewater.The paper studied the acid extraction and salting-out separation processes toextract pectin from citrus processing wastewater. The type of salt, salt dosage andinitial pH of pectin extract on the effect of pectin extraction yield were exmined.Finally it is concluded that the best conditions for the extraction of pectin: A12(SO4)3as pectin precipitation agent, dosage of A12(SO4)3was8%(w/v), the initial pH of5.0of pectin extract in the process of settling-out. Under the condition of the above, afterextraction and separation, pectin extraction yield from the acid and alkali wastewaterproduced by canned industry maximized68.8%, correspondingly the value of the totalcitrus processing wastewater outfalls reached the highest value69.7%. These twomethods solved the problem how to remove pectin from wastewater better. At the sametime they can achieve the effect of from waste to resource utilization, alleviate thepressure the pectin yield was low in our country, accorded with the requirement ofenergy conservation and emissions reduction in today’s society.Penicillium simplicissimum was applied to pectins removal from wastewater ataerobic condition. The effects of the concentration of pectins, reaction duration, typeof nitrogen source, ratio of carbon to nitrogen, and pH value on pectin biodegradationwere evaluated separately. Pectin removal ranged from94.7%to97.1%when thepectin concentration ranged from500to3000mg/L. Pectin removal increased withbiodegradation time and gradually reached97.1%at120h. Ammonium sulphate was the best among the five nitrogen sources. Pectin removal maximized at C: N of6:1and initial pH value of6.0. Most pectins were decomposed into inorganic carbonaccording to the chemical oxygen demand (CODCr), and FTIR analyses showed thatsmall organic molecules produced by pectin biodegradation still existed.Polygalacturonase activity of Penicillium simplicissimum was large at high pectinsremoval. Results show that Penicillium simplicissimum is effective for pectin removalfrom wastewater, and Biodegradation by Penicillium simplicissimum CGMCC3.3241for the treatment of citrus processing wastewater has potential application.