Coagulation of Chitin Production Wastewater from Shrimp Scraps with By-Product Chitosan and Chemical Coagulants

• Main Authors: Nguyen Van Nhi Tran, Qiming Jimmy Yu, Tan Phong Nguyen, San-Lang Wang
• Format: Article
• Language: English
• Published: MDPI AG 2020-03-01
• Series: Polymers
• Subjects: high strength wastewater treatment; turbidity removal; chitin and chitosan; chemical coagulation; crude protein recovery
• Online Access: https://www.mdpi.com/2073-4360/12/3/607

Chitin production wastewater contains nutrient-rich organic and mineral contents. Coagulation of the wastewater with a natural coagulant such as by-product chitosan would be an economical and environmentally friendly method of treatment. This study investigated the treatment efficiencies of a preliminary sedimentation process followed by coagulation. The removal efficiencies for wastewater parameters were evaluated and compared for coagulants including by-product chitosan, polyaluminum chloride, and polyacryamide. The evaluation was based on the removal of wastewater turbidity and other criteria, including tCOD, sCOD, TKN, NH₄⁺−N, TP, TSS, calcium, and crude protein. The results showed that the preliminary sedimentation (before coagulation) can remove over 80% of turbidity and more than 93% of TSS at pH 4 in 30 min. At optimal conditions, when the ratio of crude protein and calcium was 4.95, by-product chitosan dose of 77.5 mg·L^−¹ and pH = 8.3, the wastewater characteristics changes were tCOD 23%, sCOD 32%, TKN and ammonium 25%, TP 90%, TSS 84%, Ca²⁺ 29%, and crude protein 25%. The residue recovered through coagulation consists of up to 55 mg·g^−¹ crude protein, which is used for animal feed or crop fertilizer.