Elsevier

Desalination

Volume 285, 31 January 2012, Pages 1-13
Desalination

Removal of total ammonia nitrogen (TAN), nitrate and total organic carbon (TOC) from aquaculture wastewater using electrochemical technology: A review

https://doi.org/10.1016/j.desal.2011.09.029Get rights and content

Abstract

Protein rich wastes from aquaculture systems result in total ammonia nitrogen (TAN), total organic carbon (TOC) and biochemical oxygen demand (BOD). A number of conventional approaches have been adopted for the removal of these wastes in aquaculture ponds and hatcheries with varying degrees of success but they face critical problems such as membrane fouling, high cost or the generation of toxic by-products. To overcome such issues, electrochemical technology is commonly employed. The advantages of electrochemical treatment include high efficiency, ambient operating conditions, small equipment sizes, minimal sludge generation and rapid start-up. An even better system involves bio-electrochemical reactors (BERs), which have the potential to generate energy from wastewater (by means of microbial fuel cells) or a valuable product such as hydrogen (using microbial electrolysis cells). Mechanisms of cathodic nitrate reduction and anodic oxidation in electrochemical and bio-electrochemical technology are reported in this review. Also some work on the simultaneous removal of nitrate and organic matter by Electro-Fenton and microbial fuel cells are elaborated upon. It is apparent that BERs can remove contaminants at high efficiencies (≈ 99%) whilst giving least impact upon the environment.

Highlights

► Conventional nitrate and organic carbon removal generate environmental issues. ► Electrochemical technology can remove both contaminants in a green manner. ► Mechanisms of contaminant removal in electrochemical reactors are discussed. ► Mechanisms of contaminant removal in bio-electrochemical reactors are discussed. ► 99% removal of organic matter and nitrate achieved with bio-electrochemical cell.

Introduction

Aquaculture globally has undergone tremendous growth during the last 50 years from a production of less than a million tons in the early 1950s to over 50 million tons during the present time. Aquaculture in Malaysia has developed greatly from small scale family oriented businesses to large scale operations. Exports of aquaculture have recorded positive growth rates as much as RM 1,323,280 (US$ 440,000) to RM 1,769,305 (US$ 587,120) from 2007 to 2008 [1], [2]. The main categories of fish involved have been shellfish, freshwater fish, marine prawn, marine fish and giant freshwater prawn [3]. Fish or fish based products are a cheap source of animal protein for human growth. Due to Malaysia being surrounded by sea and an ocean, it is easy to have access to fish and fish based products [2]. The total consumption of fish has increased from 49 kg/capita/year to 56 kg/capita/year from year 2000 to 2010. Hence, Malaysia has the highest fish consumption rate in the world [1], [2]. Current local production of fisheries, which has increased from 89% in year 2000 to 94.3% in 2010 [1], is unable to achieve the goal of self sufficiency in the future. This is due to an increase in health awareness and rise of population in the country. Thus, in year 2009, through National Aquaculture Development Plan, the Ministry of Agriculture has roughly allocated RM 358 million (US$ 118,796,770) to establish an aquaculture industrial zone and provide the necessary assistance, including infrastructure to cope with the rising demand [3].

The intensive development in the aquaculture industry has caused major environmental impacts. Wastewater discharged from aquaculture contains nitrogenous compounds (ammonia, nitrite and nitrate), phosphorus and dissolved organic carbon, which cause environmental deterioration at high concentrations [4]. Ammonia (NH3) is the product of fish respiration and decomposition of excess organic matter. Chemoautotrophic bacteria (Nitrosomonas and Nitrobacter) tend to oxidize ammonium ions (NH4+) to nitrite (NO2-) and nitrate (NO3-) ions. Nevertheless, these ions are removed by aquatic plants, algae and bacteria since they assimilate them as a source of nitrogen [5]. These nitrogen compounds are nutrients for generating eutrophication which disrupt aquatic ecosystems in a severe manner [6] as shown in Fig. 1. Animal farming, urban and agricultural runoff, industrial wastes, and sewage effluents also increase the concentration of ammonium, nitrate and nitrite ions in aquatic ecosystems [5]. Several studies have been conducted on the toxicity of nitrate on aquatic animals and results indicate that nitrate reacts with hemoglobin causing shortage of oxygen in their body (methaemoglobin) and finally death [5]. When nitrate enters in human intestines, it is also converted into nitrite under anaerobic conditions and this may lead to methaemoglobinaemia in infants [4], [5]. Besides that, formation of nitrosoamines from nitrite can give rise to cancers of the digestive tract since nitrosamines are the most efficacious carcinogens in mammals [7]. Therefore, World Health Organization (WHO) established the limit for nitrate in drinking water to 10 mg NO3-N/L [7], [8].

Total organic carbon (TOC) is defined as any compound containing carbon atoms except CO2 and related substances such as carbonate, bicarbonate and the like [10]. Various natural and man-made activities result in the presence of dissolved organic carbon in aquaculture wastewater. The major compositions of dissolved organic carbon in aquaculture wastewater are humic-like substances, carbohydrates, protein-like substances, low molecular weight aldehydes, fulvic acids, phenols and organic peroxides [11]. Organic carbon is the energy substrate for many microorganisms and its consumption contributes to the problem of inadequate dissolved oxygen in water bodies that become a threat to aquatic life. In addition, treatment costs increase when dissolved organic carbon in wastewater is high [4], [11], [12], [13]. In this article, the removal of conventional TAN, nitrate and organic matter is reviewed in detail. In addition, the review attempts to compare both electrochemical and bio-electrochemical methods used for TAN or nitrate and total organic removal. Finally, an effective method for simultaneous denitrification and TOC removal in synthetic contaminated water and actual aquaculture wastewater is surveyed and recommendations are put forth with some emphasis on a novel bio-electrochemical reactor.

Section snippets

Conventional TAN and nitrate removal methods

Coagulation, filtration, chlorination, UV and ozone treatment are the common methods applied in wastewater treatment but are not considered advanced enough for TAN and nitrate ions removal. So, there are a few techniques available to remove TAN and nitrate ions that are divided into two main categories: physicochemical and biological (Table 1).

Conventional TOC removal methods

Lowering organic carbon concentrations in recirculating aquaculture systems can enhance denitrification since bacteria that consume organic carbon compete directly for space and oxygen with those bacteria that consume ammonia and nitrite [62]. There are a few practical approaches for removal of low levels of TOC (< 10 ppm) in water, which are adsorption and oxidation. Oxidation treatments include ozonation and UV radiation. These processes are briefly reviewed below.

Electrochemical technology

The conventional methods do help with nitrate and organic carbon removal but the disadvantages include sludge production, high energy demand, unstable performance and frequent maintenance requirements [15], [26]. Hence, research on new methods for nitrate and organic carbon removal in aquaculture wastewater is under way. The past few decades has seen the emergence of electrochemical technology for wastewater treatment. The particular advantages of electrochemical treatment include high

Bio-electrochemical technology

Bio-electrochemical systems (BESs) are divided into two major groups which are microbial fuel cells (MFCs) and microbial electrolysis cells (MECs). They have great potential for simultaneous production of energy as well as for wastewater treatment. These systems use microorganisms for catalysis of electrochemical reactions [97], [98]. In MFCs, chemical energy of organic material in wastewater is converted into electrical energy, while in MECs, external electricity is utilized to generate a

Conclusion

The literature reports several physicochemical and biological methods for the removal of TAN, nitrate and TOC. However, they face critical issues such as membrane fouling or generation of toxic by-products that limit their successful application in the field. The electrochemical method could be a good alternative due to its high efficiency, ambient operating conditions, small equipment sizes, minimal sludge generation and rapid start-up. However, the generation of ammonia and nitrite limit its

Acknowledgement

The authors would like to acknowledge the University of Malaya Research Grant RG096/10AET for funding this research.

References (121)

  • M.B. Timmons et al.

    Application of microbead biological filters

    Aquac. Eng.

    (2006)
  • A.D. Greiner et al.

    Evaluation of the nitrification rates of microbead and trickling filters in an intensive recirculating tilapia production facility

    Aquac. Eng.

    (1998)
  • J. Davidson et al.

    Fluidized sand biofilters used to remove ammonia, biochemical oxygen demand, total coliform bacteria, and suspended solids from an intensive aquaculture effluent

    Aquac. Eng.

    (2008)
  • R. Crab et al.

    Bio-flocs technology application in over-wintering of tilapia

    Aquac. Eng.

    (2009)
  • Y. Avnimelech

    Carbon/nitrogen ratio as a control element in aquacultural systems

    Aquaculture

    (1999)
  • Y.F. Lin et al.

    Nutrient removal from aquaculture wastewater using a constructed wetlands system

    Aquaculture

    (2002)
  • M.D. Afonso et al.

    Brackish groundwater treatment by reverse osmosis in Jordan

    Desalination

    (2004)
  • Y.M. Kim et al.

    Overview of systems engineering approaches for a large-scale seawater desalination plant with a reverse osmosis network

    Desalination

    (2009)
  • N. Hilal et al.

    A comprehensive review of nanofiltration membranes: treatment, pretreatment, modelling, and atomic force microscopy

    Desalination

    (2004)
  • J.A. Lopez-Ramirez et al.

    Comparative studies of reverse osmosis membranes for wastewater reclamation

    Desalination

    (2006)
  • C.C.K. Liu et al.

    Experiments of a prototype wind-driven reverse osmosis desalination system with feedback control

    Desalination

    (2002)
  • D. Hasson et al.

    Inception of CaSO4 scaling on RO membranes at various water recovery levels

    Desalination

    (2001)
  • A.M.M. Sakinah et al.

    Fouling characteristic and autopsy of a PES ultrafiltration membrane in cyclodextrins separation

    Desalination

    (2007)
  • I. Koyuncu et al.

    Bench-scale assessment of pretreatment to reduce fouling of salt-rejecting membranes

    Desalination

    (2006)
  • B. Gemende et al.

    Tests for the application of membrane technology in a new method for intensive aquaculture

    Desalination

    (2008)
  • G. Oron et al.

    A two stage membrane treatment of secondary effluent for unrestricted reuse and sustainable agricultural production

    Desalination

    (2006)
  • S. Velizarov et al.

    Removal of inorganic charged micropollutants from drinking water supplies by hybrid ion exchange membrane processes

    Desalination

    (2008)
  • V. Roquebert et al.

    Electrodialysis reversal (EDR) and ion exchange as polishing treatment for perchlorate treatment

    Desalination

    (2000)
  • J.H. Xu et al.

    Perchlorate removal by granular activated carbon coated with cetyltrimethyl ammonium chloride

    Desalination

    (2011)
  • M. Shrimali et al.

    New methods of nitrate removal from water

    Environ. Pollut.

    (2001)
  • K.A. Karanasios et al.

    Hydrogenotrophic denitrification of potable water: a review

    J. Hazard. Mater.

    (2010)
  • H. Strathmann

    Electrodialysis, a mature technology with a multitude of new applications

    Desalination

    (2010)
  • V.M. Monsalvo et al.

    Activated carbons from sewage sludge: application to aqueous-phase adsorption of 4-chlorophenol

    Desalination

    (2011)
  • R. Crab et al.

    Nitrogen removal techniques in aquaculture for a sustainable production

    Aquaculture

    (2007)
  • E.H. Eding et al.

    Design and operation of nitrifying trickling filters in recirculating aquaculture: a review

    Aquac. Eng.

    (2006)
  • S.T. Summerfelt

    Design and management of conventional fluidized-sand biofilters

    Aquac. Eng.

    (2006)
  • R. Moore et al.

    The effect of media size on the performance of biological aerated filters

    Water Res.

    (2001)
  • Y.J. Chan et al.

    A review on anaerobic-aerobic treatment of industrial and municipal wastewater

    Chem. Eng. J.

    (2009)
  • P. Chowdhury et al.

    Biological treatment process for fish processing wastewater — a review

    Bioresour. Technol.

    (2010)
  • M.A. Burford et al.

    Nutrient and microbial dynamics in high-intensity, zero-exchange shrimp ponds in Belize

    Aquaculture

    (2003)
  • S. Zhu et al.

    Effects of organic carbon on nitrification rate in fixed film biofilters

    Aquac. Eng.

    (2001)
  • C. Schulz et al.

    Treatment of rainbow trout farm effluents in constructed wetland with emergent plants and subsurface horizontal water flow

    Aquaculture

    (2003)
  • Y.F. Lin et al.

    Performance of a constructed wetland treating intensive shrimp aquaculture wastewater under high hydraulic loading rate

    Environ. Pollut.

    (2005)
  • V. Krumins et al.

    Part-day ozonation for nitrogen and organic carbon control in recirculating aquaculture system

    Aquac. Eng.

    (2001)
  • S.J. Aitcheson et al.

    Removal of aquaculture therapeutants by carbon adsorption: 1. Equilibrium adsorption behavior of single components

    Aquaculture

    (2000)
  • F. Aloui et al.

    Performances of an activated sludge process for the treatment of fish processing saline wastewater

    Desalination

    (2009)
  • M.S. Tango et al.

    Impact of ozonation on water quality in marine recirculation system

    Aquac. Eng.

    (2003)
  • G.L. Bullock et al.

    Ozonation of a recirculating rainbow trout culture system: I. Effects on bacterial gill disease and heterotrophic bacteria

    Aquaculture

    (1997)
  • S.T. Summerfelt et al.

    Process requirements for achieving full- flow disinfection or recirculating water using ozonation and UV irradiation

    Aquac. Eng.

    (2009)
  • C.I.M. Martins et al.

    New developments in recirculating aquaculture systems in Europe: a perspective on environmental sustainability

    Aquac. Eng.

    (2010)
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