Constructed wetlands for treatment of harvest effluents from grow-out ponds of the Amazon river prawn

Abstract

Effluent discharges from aquaculture can reduce water quality in receiving water bodies and that strategies or practices to reduce this are necessary. One possibility is to reduce, or eliminate, water renewal in grow‐out ponds. In this study, we eliminated water renewal in grow‐out ponds associated with the culture of 40 individuals m−2 of Amazon river prawn (Macrobrachium amazonicum). At the end of the culture period it was, however, necessary to drain the pond to harvest the prawns. An experiment was performed in triplicate, in which the water supply characteristics and harvest water characteristics of ponds were evaluated. To reduce these concentrations of total N and P, an aquatic macrophyte (Eichhornia crassipes, water hyacinth) treatment system (CWs) was adopted. The water characteristics in the CWs were evaluated after 1, 3, 7, 14 and 21 days. The water supply of ponds presented the average concentrations of 0.67 ± 0.32 mg L−1 and 17.4 ± 14.7 μg L−1 of total‐N and total‐P respectively. The harvest effluent of ponds had elevated concentrations of different forms of nitrogen (4.44 mg L−1 of total‐N) and phosphorous (100.9 μg L−1 of total‐P). After 1 day of the experiment we found the following reductions in key nutrients in treatment system containing E. crassipes: 90%, 78% and 45% reductions in the concentrations of particulate matter, orthophosphates and nitrates respectively. We noted that after 3 days the nitrates had been reduced by 53%. We concluded that 3 days of this treatment was sufficient for the removal of the additional nutrients that had accumulated in the Amazon river prawn ponds.

Nitrogen and phosphorus flux from the production of Nile tilapia through the application of environmental indicators

“…During the withdrawal of fish period, large volumes of water are dropped to the environment and, in many cases without prior treatment, can lead to situations where the pollutant concentrations are high enough to generate localized impacts (Boyd et al, 2007;Santos and Camargo, 2014).…”

Tratamento de efluente de aquicultura com macrófitas flutuantes: revisão sistêmica e metanálise

“…Os gêneros das espécies de macrófitas flutuantes encontrados nos trabalhos foram Eichhornia (15), Pistia (7), Lemna (6), Salvinia (5) e Azolla (2), nessa ordem (Figura 4). O gênero Eichhornia em sistema de wetland construído obteve remoção de 90% do fósforo total e 75% do nitrogênio total de efluente de aquicultura de Oreochromis niloticus (Henry- Silva & Camargo, 2006;Oliveira Santos & Camargo, 2015). A taxa de remoção em efluente de carcinicultura para sólidos suspensos foi até 72%, turbidez redução até 55% e a demanda bioquímica de oxigênio com até 40% de remoção (Lin et al, 2010).…”

Fish farming in cages: a practice to be restricted in Brazil

“…However, IMTA cannot be used in fish cages installed in Brazilian reservoirs for technical reasons, for example, since there is no commercial freshwater mollusks species with established culture technology. In addition, floating aquatic macrophytes can be used to efficiently treat aquaculture effluents in earthen ponds (Santos & Camargo, 2015;Osti et al, 2018), removing the nutrients in the surface portion of the water column, however, probably they will not efficiently remove nutrients produced by net cages that have been installed a minimum deep of 2.0 meters approximately. We emphasize that polycultures in Brazil, using species with different feeding habits, are only used in earthen ponds with the same concepts of IMTA systems.…”