Abstract
Biological wastewater treatment processes such as activated sludge and anaerobic digestion remain the most favorable when compared to processes such as chemical precipitation and ion exchange due to their cost-effectiveness, eco-friendliness, ease of operation, and low maintenance. Since Abattoir Wastewater (AWW) is characterized as having high organic content, anaerobic digestion is slow and inadequate for complete removal of all nutrients and organic matter when required to produce a high-quality effluent that satisfies discharge standards. Multi-integrated systems can be designed in which additional stages are added before the anaerobic digester (pre-treatment), as well as after the digester (post-treatment) for nutrient recovery and pathogen removal. This can aid the water treatment plant effluent to meet the discharge regulations imposed by the legislator and allow the possibility for reuse on-site. This review aims to provide information on the principles of anaerobic digestion, aeration pre-treatment technology using enzymes and a hybrid membrane bioreactor, describing their various roles in AWW treatment. Simultaneous nitrification and denitrification are essential to add after anaerobic digestion for nutrient recovery utilizing a single step process. Nutrient recovery has become more favorable than nutrient removal in wastewater treatment because it consumes less energy, making the process cost-effective. In addition, recovered nutrients can be used to make nutrient-based fertilizers, reducing the effects of eutrophication and land degradation. The downflow expanded granular bed reactor is also compared to other high-rate anaerobic reactors, such as the up-flow anaerobic sludge blanket (UASB) and the expanded granular sludge bed reactor (EGSB).
Highlights
The continuous influx and increase in urbanization and industrialization have led to an increase in the consumption of goods and services
Relative to other commodities such as winery and car manufacturing, the abattoir industries have increased and doubled in production in the past decade, increasing water consumption. This increase in water consumption inevitably poses a threat to the environment due to added pollution and increasing water scarcity such that by 2050 global water demand is projected to be 20–30% higher than current levels given both population growth and socio-economic development [1].This is caused by the presence of organic matter such as chemical oxygen demand (COD), which poses a threat to the environment by accelerating the deoxygenation of rivers and contamination of ground water [2]
More physio-biological pretreatment options and parameter optimization can be a way to ensure limited fouling and maintain a minimal pollution footprint. Whilst biological processes such as anaerobic and aerobic digestion provide the muchneeded benefits of being environmentally friendly and economical, they still fall short in nutrient removal, digesting FOGs, and removing suspended solids
Summary
The continuous influx and increase in urbanization and industrialization have led to an increase in the consumption of goods and services. Relative to other commodities such as winery and car manufacturing, the abattoir industries have increased and doubled in production in the past decade, increasing water consumption. This increase in water consumption inevitably poses a threat to the environment due to added pollution and increasing water scarcity such that by 2050 global water demand is projected to be 20–30% higher than current levels given both population growth and socio-economic development [1].This is caused by the presence of organic matter such as chemical oxygen demand (COD), which poses a threat to the environment by accelerating the deoxygenation of rivers and contamination of ground water [2].
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