Abstract
A novel liquid chitosan-based biocoagulant for treating wastewater from a Moroccan fish processing plant was successfully prepared from shrimp shells (Parapenaeus longirostris), the most abundant fish by-products in the country. The shells were characterized using scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and Fourier transforms infrared spectroscopy. Using chitosan without adding acetic acid helps to minimize its negative impact on the environment. At the same time, the recovery of marine shellfish represents a promising solution for the management of solid fish waste. In order to test the treatment efficiency of the biocoagulant developed, a qualitative characterization of these effluents was carried out beforehand. The optimization process was conducted in two steps: jar-test experiments and modeling of the experimental results. The first step covered the preliminary assessment to identify the most influential operational parameters (experimental conditions), whereas the second step concerned the study of the effects of three significant operational parameters and their interactions using a Box–Behnken experimental design. The variables involved were the concentration of coagulant (X1), the initial pH (X2), and the temperature (X3) of the wastewater samples, while the responses were the removal rates of turbidity (Y1) and BOD5 (Y2). The regression models and response surface contour plots revealed that chitosan as a liquid biocoagulant was effective in removing turbidity (98%) and BOD5 (53%) during the treatment. The optimal experimental conditions were found to be an alkaline media (pH = 10.5) and a biocoagulant dose of 5.5 mL in 0.5 L of fish processing wastewater maintained at 20 °C.
Highlights
Wastewater effluents from fish processing plants present an environmental issue because of complications in their treatment due to the different components presented in the effluents
The different mixtures of raw shrimp shells were observed to identify the elemental composition of the material (Figures 2 and 3)
Various structures visualized by scanning electron microscope (SEM) were analyzed using energy dispersive X-ray analysis (EDX)-SEM images
Summary
Wastewater effluents from fish processing plants (fish processing wastewater, FPW) present an environmental issue because of complications in their treatment due to the different components presented in the effluents. This sector generates USD 207,407,800.00 per year on export [1]. In Morocco, the subject of this study, the effluent volume is increasing, but the fish processing industry is responsible for a large quantity of fishrelated solid wastes, including bones, skins, scales, fins, and swim bladders, constituting 36% (and maybe representing up to 60%) of the raw material mass [2,3]. The rejected by-products can be involved (by using the proposed methodology) in the preparation of products for wastewater treatment
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