Adsorption of aquaculture pollutants using a sustainable biopolymer

Abstract

Intensive aquaculture needs to adopt techniques that are able to contribute towards sustainability. Closed systems that employ water recirculation can combine intensive production with environmental sustainability, since there is no exchange of water or discharge of effluents into the environment. In order to achieve this, effective filtration systems are required to ensure that the water quality is satisfactory for the cultivation of aquatic organisms. Chitosan, an industrial waste material derived from crustacean farming, is a renewable natural material that is biodegradable and possesses adsorbent characteristics. In this work, chitosan foam was incorporated in filters and was evaluated as an adsorbent of aquaculture pollutants, adding value to the material and at the same time providing a use for industrial waste. The foam was characterized by scanning electron microscopy and energy dispersive spectroscopy, apparent density, and water absorption capacity. It was used to remove ammonia, nitrite, orthophosphate, and turbidity from aquaculture effluents. The foam consisted of a bilayer with smooth and porous sides, which presented low density, flexibility, and high water absorption capacity. The best proportion of the foam, in terms of the mass of foam per volume of solution (% m v), was 0.10, which resulted in removal of 32.8, 57.2, 89.5, and 99.9% of ammonia, nitrite, orthophosphate, and turbidity, respectively. This biopolymer produced is biodegradable, and when saturated with organic compounds from aquaculture, and no longer suitable for reuse as a filter material, it can be employed as a fertilizer, hence closing the sustainability cycle of the aquaculture production chain.

Evaluation of Nutrient Removal Efficiency with Chitosan: Nutrient Composition and Bacterial Removal in Effluents of Nile Tilapia (Oreochromis niloticus) in the Hatchery

“…The presence of reactive hydroxyl functional group (-OH) and amine (-NH2) in the chitosan chemical structure makes it effective as an adsorbent material for the removal of contaminants from wastewater [7]. A high percentage of nitrogen on the porous surface of chitosan suggests the existence of an amino-functional group that facilitates adsorption interactions between chitosan and wastewater molecules [31]. The modified or treated chitosan that develops by grafting amino, ), in disagreement with the views of Wu FC, et al [35].…”

“…Thereafter, the contents were filtered and washed with deionized water until the neutral pH 7 was attained. The resulting chitosan was dried at 60°C for 24 hours in the oven at 60°C [31]. The stepwise process followed for production of chitosan is shown in flow chart (Figure 2).…”

Benthic-based contributions to climate change mitigation and adaptation

“…R. Soc. B 375: 20190107 and fish are being farmed in closed recirculation systems on land with no discharge, achieved using biodegradable biopolymers to absorb waste products [121]. Such systems provide food security as well as economic and social benefits, such as social cohesion, educational value and livelihood enrichment [122].…”

Comparative Study of Biodegradation and Coagulation of Dairy Effluent by Using Immobilized Microbial Isolates and Chitosane Silver Nano Particles and Production Biodiesel

“…At elevated concentrations, ammonia can be an environmental problem due to its toxicity, especially to aquatic organisms [41]. It was observed that the concentration ammonia was decreased after filtration by zeolite to 12 mg/l with removal efficiency (45.9%) and after treatment by chitosan-Ag nanoparticle , it was observed the resulted in greater efficiency of removal of ammonia from the effluent (Figure 7), due to the increased surface area of the adsorbent and the availability of more adsorption sites.…”