Waste System: Its Utility and Analyses in Aquaculture

Understanding and approaches towards circular bio‐economy of wastewater reuse in fisheries and aquaculture in India: An overview

“…phosphorus and nitrogenous nutrients, and, suspended solids 83 . Nitrogen, phosphorus and carbon represent the huge quantum of elements in aquaculture wastewater that are targeted for valorization 84–90 . Under minimal or zero‐water exchange and, hyper‐intensive and/or intensive culture systems, bioflocs composed of a galaxy of microorganisms, protozoa, algae, uneaten feed particles, faeces and physical debris, can be used as nutrients for selective species of fish and shrimps under reasonably controlled density 91,92 .…”

“…The system necessarily operates on the rational manoeuvring of an optimal C:N ratio (10:1–15:1) through calculated purging with suitable, low‐cost carbohydrates. In biofloc systems, some of this nitrogen is incorporated into bacterial cells as microbial protein which in turn contributes to growth 86,87,125 . Biofloc technologies facilitate intensive culture with zero or minimal water exchange, while reducing investment and maintenance costs.…”

“…Following stabilization of effluents, they are stocked with advanced carp fingerlings at the rate of 7000–10,000 nos./ha 150 . In general practice, farming is done following multiple stocking and multiple harvesting mode where the rearing period is 3–5 months or growth of the cultured fish up to 250–400 g of marketable size 86,150 . Indian major and minor carps, Israeli carp, silver carp, bighead carp, grass carp, common carp, catfish, largemouth bass, tilapia, freshwater prawns are considered as suitable species 151 under this particular culture habitat.…”

“…83 Nitrogen, phosphorus and carbon represent the huge quantum of elements in aquaculture wastewater that are targeted for valorization. [84][85][86][87][88][89][90] Under minimal or zero-water exchange and, hyper-intensive and/or intensive culture systems, bioflocs composed of a galaxy of microorganisms, protozoa, algae, uneaten feed particles, faeces and physical debris, can be used as nutrients for selective species of fish and shrimps under reasonably controlled density. 91,92 High cost of production in fish farming can be reduced by transforming hazardous nitrogenous wastes from aquaculture production system into value added protein rich marketable produce thereby increasing the income and securing sustainability.…”

“…In biofloc systems, some of this nitrogen is incorporated into bacterial cells as microbial protein which in turn contributes to growth. 86,87,125 Biofloc technologies facilitate intensive culture with zero or minimal water exchange, while reducing investment and maintenance costs. This technology is a unique example of circular economy in material flow as it is inherent with the potential to in situ convert autochthonous generation of nitrogenous waste from the protein feed applied in the production process back to single cell microbial protein thereby maximizing biosecurity while minimizing external environmental fall-outs.…”