Biological denitrification and physico-chemical treatment for removing contaminants and toxicity in wastewater generated by shrimp farming

The current water crisis intensifies concerns related to food production, especially in the agro-industrial sector. Shrimp farming is one of the most water-intensive aquaculture activities, generating large volumes of effluents, which, when released directly into water bodies without treatment, can cause a series of environmental impacts. Considering the environmental problems associated with shrimp farming, treating wastewater prior to disposal is essential to maintain the economic viability and environmental sustainability of this activity. Thus, the aim of this study was to evaluate the efficiency of the biological denitrification and physico-chemical treatment for removing contaminants and toxicity in wastewater generated by shrimp farming. A wastewater sample was subjected to biological treatment, to remove nitrogen (nitrate and nitrite) using a natural bamboo biomass as a source of denitrifying microorganisms. The residue was then submitted to physico-chemical treatment using coagulation/flocculation, adsorption with activated carbon and disinfection. The contamination risk was assessed applying an acute toxicity test (Daphnia magna). The combination of treatment techniques applied provided satisfactory results for contaminant removal, with an average efficiency above 95% for nitrogen (nitrate and nitrite), 97.5% for color, 99% for turbidity, 99% for suspended solids, 48.2% for COD and 88.9% for BOD5. In addition, the acute toxicity assessment of the treated wastewater indicated a reduction for 2 TF (no toxic), reaching a value within the maximum limits established by current legislation.