Implementation of a constructed wetland for the sustainable treatment of inland shrimp farming water

Thi Thu Hang Pham,Vincent Cochevelou,Hoang Dang Khoa Dinh,Florian Breider,Pierre Rossi

doi:10.1016/j.jenvman.2020.111782

Abstract

In the Mekong delta, inland-based shrimp breeding requires significant inflow of high-quality freshwater. In turn, discharge of substantial loads of poor-quality effluents negatively impacts adjacent water bodies and favors disease outbreaks. This project describes the implementation of a laboratory-based continuous closed recirculation aquaculture system composed of a constructed wetland (CW) with horizontal subsurface flow as a water treatment filter for mesohaline conditions, functioning under high loading rate (HLR = 1.54 m/d with HRT = 1.31 h). This CW was equipped of successive compartment dedicated to the successive elimination of the contaminants of interests. CW performance was measured over a complete growth cycle of the White-leg shrimps (Litopenaeus vannamei). Results showed that the designed system was pertinent, improving water quality of the shrimp culture substantially. Complete removal of nitrite was attained, with a concomitant reduction of respectively 78% and 76% of nitrate and COD. Bacteria enumeration tests showed that Vibrio sp. cells were fully removed, and that a 3 Log reduction was reached in total aerobic bacteria.

Highlights

Over the last 30 years, world production of cultivated aquatic food has increased rapidly and has driven aquaculture to be one of the fastestgrowing animals-food-producing sectors (Letchumanan et al, 2015)
Our objectives were reached by testing the water cleaning capacity of the constructed wetland (CW) in laboratory conditions during an intensive culture cycle of White-leg shrimps (Litopenaeus vannamei), allowing to evaluate the performance and to identify key mechanisms involved in this experimental system
The determining parameter is the surface occupied by the CW as well as the water volume ratio between the CW and culture tank

Summary

Introduction

Over the last 30 years, world production of cultivated aquatic food has increased rapidly and has driven aquaculture to be one of the fastestgrowing animals-food-producing sectors (Letchumanan et al, 2015). Pond water and sediments remaining after one round of shrimp culturing are released into natural water bodies without any treatment, inducing strong eutrophication and salinization pro cesses (Lan, 2013). These culturing systems rely massively on pesticides and antibiotics (ABs) to avoid shrimp disease outbreak (Rico and Van der Brick, 2014). 700 g of ABs is used per ton of cultured fish, seven times more than other countries, resulting in a high prevalence of residual concentrations in aquaculture products and waste (Uchida et al, 2016).

Objectives

Methods

Results