Chitosan Extraction for Coagulation Processes and Solid Recovery

Chitosan was extracted from Macrobrachium rosenbergii and Penaeus monodon using modified chemical sequences involving demineralization, deproteinization, decolouration, and deacetylation. Four extraction pathways were evaluated, and sequence four (DC-DM-DP-DA) produced chitosan with significantly higher degree of deacetylation (DDA) and solubility (p 0.05) in both species. Increasing alkali concentration and temperature under the traditional sequence further improved physicochemical properties. Although carapace yielded more chitosan (84.31%) than legs (75.86%), leg-derived chitosan showed superior solubility (80%) and DDA (91%). The extracted chitosan effectively treated shrimp aquaculture wastewater, significantly reducing turbidity, TSS, colour, ammonia, nitrite, and salinity, with statistical models confirming good fit. Recovered floc contained essential plant nutrients (N, P, K, Ca, Mg) and enhanced Ipomoea aquatica growth beyond commercial fertilizer. Improved growth was linked to higher nitrogen content (6.04%) in floc derived from M. rosenbergii chitosan.