A novel treatment process for dairy wastewater with chitosan produced from shrimp-shell waste

Abstract

Recovery of proteins and fats from dairy wastewater has two advantages: the recovery process results in a pretreatment of wastewater prior to discharge to municipal sewers; and the recovered sludge can be used as a food additive. Carboxy Methyl Cellulose (CMC) is commonly used for the treatment of dairy wastewater after reducing the wastewater to pH 4.2. A novel application of a non-toxic cationic biopolymer – chitosan – is evaluated as a substitute for CMC. The results indicate that chitosan can achieve results similar to the CMC process even at pH as high as 5.3. Thus, the novel method can save up to 50 % of pH-adjusting chemicals requires for both for acidification and neutralisation. The process sludge contains valuable components which have been evaluated and found to be suitable as a food additive. A stable demand for chitosan is also expected to solve the existing shrimp-shell waste disposal problems along the west and north Norwegian coasts. The process is found to be both environmentally and economically attractive for all partners.