Environmental Impacts of Wastes and Contaminants from Aquaculture and Their Remediation Techniques

World food production needs to increase as the human population is increasing too steadily over the years. On the other hand, global food production sectors are being compromised at an alarming rate due to urbanization and industrialization. Aquaculture and capture fisheries are the two major food-producing sectors with a huge potential to feed the growing population. Aquaculture production has been the fastest food-producing sector in the world for the past several decades; on the other hand, a world capture fishery has stagnated over the last two decades and is expected to continue in such a manner for the coming years. Therefore, to meet the global demand for fish with relatively stable capture fisheries, world aquaculture production will need to increase. Hence, the intensification of aquaculture has appeared as a feasible substitute to strengthen food fish production to fulfill the breach in supply. However, this increase in aquaculture intensification requires amplified inputs, such as feed and drugs, which, in turn, increases the ecological effects of the sector and compromises its sustainability. Although the environmental impacts of intensive aquaculture are multifaceted, wastes and contaminants produced from aquaculture setups, such as nutrients (N and P) and chemicals, (Therapeutics, disinfectants, herbicides, and insecticides) contribute the highest share. As a result of this wastes and contaminants eutrophication and public health concerns due to chemical residues in aquaculture products have been most discussed in the past. As a result of the abovementioned concerns about the impacts of aquaculture, several techniques with different approaches have been in place in the past to mitigate these environmental impacts. Among are, integrated agriculture aquaculture systems (IAA), integrated multi-trophic aquaculture systems (IMTA), recirculating aquaculture systems (RAS), and limited and/or zero water exchange systems (biofloc technology) as the main water reuse systems while removal of nutrients (nitrogen and phosphorus) and chemical contaminants from aquaculture effluents through nitrogen removal techniques and use of natural or constructed wetlands are the main approaches currently employed to treat wastes and contaminants in intensive aquaculture. Therefore, in this review, an overview of the environmental impacts of aquaculture and the mitigation techniques mentioned above are discussed in detail.