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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.

The composition of challenging matrices must be fully understood in order to determine the impact of the matrix and to establish suitable treatment methods. Rendering condensate wastewater is a complex matrix which is understudied. It is produced when the vapour from rendering facilities (heat processing of slaughterhouse waste material) is cooled as a liquid for discharge. This study offers a full physicochemical characterisation of rendering condensate wastewater and its potential for valorisation via production of viable by-products. A study of seasonal variation of levels of dissolved oxygen, chemical oxygen demand, total nitrogen and ammonia was carried out on the wastewater. The results show that the wastewater was high strength all year-round, with a chemical oxygen demand of 10,813 &plusmn, 427 mg/L and high concentrations of total Kjeldahl nitrogen (1745 &plusmn, 90 mg/L), ammonia (887 &plusmn, 21 mg/L), crude protein (10,911 &plusmn, 563 mg/L), total phosphorous (51 &plusmn, 1 mg/L), fat and oil (11,363 &plusmn, 934 mg/L), total suspended solids (336 &plusmn, 73 mg/L) and total dissolved solids (4397 &plusmn, 405 mg/L). This characterisation demonstrates the requirement for adequate treatment of the condensate before releasing it to the environment. While there is a reasonably constant flow rate and dissolved oxygen level throughout the year, higher chemical oxygen demand, total nitrogen and ammonia levels were found in the warmer summer months. From this study, rendering condensate slaughterhouse wastewater is shown to have potential for production of marketable goods. These products may include ammonium sulphate fertilizer, protein supplements for animal feeds and recovery of acetic acid calcium hydroxyapatite, thus enhancing both the financial and environmental sustainability of slaughterhouse operations. This work demonstrates a valuable assessment of a complex wastewater, while taking advantage of on-site access to samples and process data to inform the potential for wastewater reuse.

Nannochloropsis sp. has received increased attention by researchers in recent years due to its complexity and abundance of lipid structures. The lipids of this microalgae species have been identified to contain large quantities of neutral lipids which are capable of producing raw materials for nutraceuticals, food additives and biofuels. The production of biodiesel has received the greatest attention as there is an increase in global demand for both more fuel and more environmentally sustainable methods to produce such resources. The greatest challenges facing industries to mass produce viable products from microalgae involve the degradation of the cell wall and extracting the fatty acid of interest due to high costs. Various studies have shown that the extraction lipids from the microalgae can greatly influence the overall fatty acid composition. Different extraction methods can re- sult in recovering higher quantities of either saturated fatty acids, monounsaturated fatty acids or polyunsatu- rated fatty acids. Biodiesel production requires higher quantities of saturated fatty acids and monosaturated fatty acids as increased quantities of polyunsaturated fatty acids result in oxidation which decreases the perfor- mance of the biodiesel. Whereas, polyunsaturated fatty acids are required in order to produce pharmaceuticals and food additives such as omega 3. This review will focus on how different in-situ extraction methods for lipid and fatty acid recovery, influence the fatty acid composition of various Nannochloropsis species (oculate, gaditana, salina and oceanica). The mechanical methods (microwave, ultrasonic and supercritical‑carbon dioxide) of extraction for Nannochloropsis sp. will be critically evaluated. The use of enzymes will also be addressed, for their ability to extract fatty acids in a more environmentally friendly manner. This paper will report on the viable byproducts which can be produced using different extraction methods.

Hydrophobic membrane contactors represent a promising solution to the problem of recycling ammoniacal nitrogen (N-NH4) molecules from waste, water or wastewater resources. The process has been shown to work best with wastewater streams that present high N-NH4 concentrations, low buffering capacities and low total suspended solids. The removal of N-NH4 from rendering condensate, produced during heat treatment of waste animal tissue, was assessed in this research using a hydrophobic membrane contactor. This study investigates how the molecular composition of rendering condensate wastewater undergo changes in its chemistry in order to achieve suitability to be treated using hydrophobic membranes and form a suitable product. The main objective was to test the ammonia stripping technology using two types of hydrophobic membrane materials, polypropylene (PP) and polytetrafluoroethylene (PTFE) at pilot scale and carry out: (i) Process modification for NH3 molecule removal and (ii) product characterization from the process. The results demonstrate that PP membranes are not compatible with the condensate waste as it caused wetting. The PTFE membranes showed potential and had a longer lifetime than the PP membranes and removed up to 64% of NH3 molecules from the condensate waste. The product formed contained a 30% concentrated ammonium sulphate salt which has a potential application as a fertilizer. This is the first demonstration of hydrophobic membrane contactors for treatment of condensate wastewater.

Microwave assisted extraction derivatization (MAED) was investigated for preparing fatty acid methyl ester (FAME) derivatives to analyse the fatty acid (FA) composition of Nannochloropsis sp. algae. This method was compared against the conventional methods of oven assisted derivatization and direct derivatization without prior extraction. The derivatized FAMEs were analysed using GC-MS to identify and quantify the FAs present. Conventional methods have been carried out for years, but they are time consuming and require high temperatures and harmful chemicals. The MAED approach developed is 5 times (15 min) faster compared to the conventional and direct derivatization methods (75 min) optimised for FA analysis of Nannochloropsis sp. algae. The MAED method recovered significantly more FAs (51 wt%) from algal samples compared to conventional (42 wt%) and direct derivatization (34 wt%). Additionally it was shown that a sample extraction step is critical to improving the derivatization yield of algal samples for both oven assisted and MAED techniques. Fourteen FA components were identified in Nannochloropsis sp. algal samples and were evaluated for their potential use for biodiesel and biopharmaceutical products. The developed MAED method allows for a rapid, robust and accurate preparation of algal samples in order to determine their FA composition.