Capacity of Caulerpa lentillifera in the Removal of Fish Culture Effluent in a Recirculating Aquaculture System

B V A S Manori Bambaranda,Takuji W Tsusaka,Krishna R Salin,Nophea Sasaki,Anong Chirapart

doi:10.3390/pr7070440

B V A S Manori Bambaranda, Takuji W Tsusaka + Show 3 more

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https://doi.org/10.3390/pr7070440

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Abstract

Aquaculture is one of the fastest growing food producing industries in the world. Aquaculture effluent contains high concentrations of inorganic nutrients. Reduction of these inorganic nutrients in aquaculture effluent is crucial for fulfilling the effluent standards or reuse of aquaculture effluent. This study investigated the effective use of green macroalga Caulerpa lentillifera as a bioremediatory species for nutrient removal from aquaculture effluent by conducting an on-station experiment and measurements. The effluent of a fish culture unit was circulated through a macroalgal culture unit every four days for a total of 60 days, allowing 15 circulations. Concentrations of inorganic nutrients (NO2−-N, NO3−-N, NH3-N, and PO43−) were measured in the integrated system consisting of a fish unit, settling unit, macroalgal unit and extra tank for water circulation in triplicates. Multiple linear regression analysis revealed that the application of the bioremediation system led to a significant reduction in nutrient concentrations within one day, and slightly further in the following two days. On average over the 15 circulations, the first one day of application decreased the concentrations of NO2−-N, NO3−-N, NH3-N, and PO43− by 0.247 mg/L, 81.6 mg/L, 0.682 mg/L, and 0.352 mg/L, respectively. Furthermore, the C:N ratio of macroalgae decreased during the 60-day application period, providing evidence of the nutrient uptake by macroalgae. Based on the European Union (EU) standard and quality criteria of France and the Joint FAO/WHO Expert Committee (JFWEC), the macroalgae grown in the integrated system were at the safe level for human consumption in terms of contents of Cd, Pb, and As. The results of our study imply that recirculating aquaculture systems utilizing C. lentillifera for biofiltration have the potential for effective treatment of aquaculture effluent integrating fish and macroalgae production.

Highlights

Aquaculture production involves the use of different types of water resources, namely freshwater, brackish water, and seawater resources
In each circulation, the nutrient concentrations in the macroalgae culture unit were highest on Day 0, which was due to the effluent that had been generated in the fish culture unit and transferred from the settling unit
C. lentillifera can be cultured with P. latipinna and that proper water quality can be maintained for the growth and production of fish and macroalgae

Summary

Introduction

Aquaculture production involves the use of different types of water resources, namely freshwater, brackish water, and seawater resources. Both inland and marine aquaculture production are increasing rapidly to fulfill the growing demand for fishery products [1]. The rapid growth of aquaculture means greater demand for water resources, and the shortage of water has become a limiting. Processes 2019, 7, 440 factor for production at existing aquaculture farms and the expansion of aquaculture facilities [2]. It is crucial to apply different culture methods and techniques for the efficient use of water resources in aquaculture [3]. Aquaculture systems are classified as extensive, semi-intensive, and intensive farming based on culture [3]. While environmentally compatible traditional aquaculture had fewer negative effects on the environments in the past [4], the current practices of intensive aquaculture require relatively high quantities of inputs such as feed, fertilizer, and chemicals, emitting considerable amounts of waste, causing environmental issues [2,5,6,7]

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