Recovery of viable ammonia–nitrogen products from agricultural slaughterhouse wastewater by membrane contactors: a review

Abstract

Efficient removal of nitrogen from wastewater is vital to ensure the safekeeping of waterways and their biota. Increased demand for meat supplies worldwide has led to increased wastewater production consisting of higher nitrogen levels. In order to reduce nitrogen treatment costs using biological denitrification, slaughterhouses need to start looking at the potential of producing by-products from wastewater. The production of viable products from industry-based wastewater has been shown to reduce treatment costs and also generate a source of revenue for the company. The sources of nitrogen in slaughterhouse wastewater are discussed, and the risk it poses to the environment and the different treatment methods are reviewed. Additionally, the need for new methods of ammonia treatment is outlined, including the potential of recovering nitrogen to produce viable products. The use of hydrophobic membranes to recover ammonia from challenging wastewaters is critically analysed and the possible implications it may encounter with slaughterhouse wastewater. The viable products which can be derived from the nitrogen in slaughterhouse wastewater are identified and studies by multiple authors show that the production of ammonium-salts can be used to aid in agricultural fertiliser production, flame retardant compositions, food additives and protein purification precipitation. A comprehensive review of studies evaluating the composition of slaughterhouse wastewater is presented, including the impact of the challenging matrix on membrane materials, which has not being reviewed to date. Additionally, a detailed discussion on how the nitrogen content is recovered using hydrophobic membranes in order to produce viable products is also presented, which has not been discussed before in relation to slaughterhouse wastewater.