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. 2020 Mar 6;12(3):607.
doi: 10.3390/polym12030607.

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

Nguyen Van Nhi Tran  1 , Qiming Jimmy Yu  1 , Tan Phong Nguyen  2 , San-Lang Wang  3
Affiliations

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

Nguyen Van Nhi Tran et al. Polymers (Basel). .

Abstract

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.

Keywords: chemical coagulation; chitin and chitosan; crude protein recovery; high strength wastewater treatment; turbidity removal.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Contour plots of sedimentation efficiency showing effects of pH and settling time.
Figure 2
Figure 2
Contour plots of turbidity removal efficiencies with coagulation showing effects of pH and coagulant dose (mg·L−1): (a) Chitosan, (b) polyaluminum chloride (PAC), (c) polyacrylamide (PAA), (d) PAC + PAA.
Figure 3
Figure 3
Turbidity removal efficiencies at different pH values with coagulant: (a) Chitosan, (b) PAC, (c) PAA, (d) PAC + PAA.
Figure 4
Figure 4
Turbidity removal efficiencies at different coagulant concentrations with coagulant: (a) Chitosan, (b) PAC, (c) PAA, (d) PAC + PAA.
Figure 5
Figure 5
Correlation between turbidity removal efficiency (TRE) and chitosan dose at pH 7.
Figure 6
Figure 6
Correlation between turbidity removal efficiency (TRE) and pH at chitosan dose of 80 mg·L−1.
Figure 7
Figure 7
Changes of characteristics of wastewater after preliminary sedimentation and coagulation at optimum experimental conditions (left axis) and removal efficiencies (right axis).
Figure 8
Figure 8
Basic components of post-treatment sediment with two experimental designs.
Figure 9
Figure 9
Effects of ratio of crude protein and calcium ion on turbidity removal efficiencies.
See this image and copyright information in PMC

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