Assessment of the herbicidal potential of greywater from salmon processing on selected invasive weed species: A model-based approach

Abstract

The increasing demand for sustainable wastewater reuse strategies in aquaculture and agroecosystems has prompted the exploration of greywater applications beyond conventional irrigation. In this study, we investigated the herbicidal potential of greywater derived from salmon processing, characterized by a total microbial load of 10⁷ log CFU/mL, total dissolved solids (TDS) of 1200 mg/L, electrical conductivity (EC) of 1800 µS/cm, pH 7.9, chemical oxygen demand (COD) of 2100 mg/L, and total organic carbon (TOC) of 600 mg/L. A model-based experimental design was developed to assess the phytotoxic effects of this nutrient- and contaminant-rich greywater on selected problematic weed species, including Amaranthus retroflexus (redroot pigweed), Chenopodium album (common lambsquarters), and Sorghum halepense (Johnsongrass). The simulation incorporated germination inhibition, biomass reduction, and chlorophyll degradation as primary endpoints. Results indicate that elevated COD and TOC levels, coupled with high microbial activity and salinity, contribute to significant growth suppression in test weeds, suggesting allelopathic and osmotic stress-mediated mechanisms. These findings support the potential integration of aquaculture-derived greywater as a low-cost, environmentally adaptive herbicidal input in weed management, particularly in organic or low-input agricultural systems. Further research is warranted to evaluate long-term soil impacts and species-specific toxicity thresholds under field conditions.

Keywords

• Greywater
• Modelling
• Herbicide
• Salmon processing waste

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