A Review of Biological Processes for Dairy Wastewater Treatment and the Effect of Physical Parameters Which Affect Their Efficiency

Abstract

The global dairy sector produces upwards of 900 million tonnes of milk each year, resulting in 2.25 billion tonnes of wastewater being generated. This is significant in the South African context as a large percentage of the population lives without reliable access to clean, reliable water. The treatment of dairy wastewater (DWW) in this context would help alleviate the unavailability for many people in this country. DWW has a high fat content along with a high chemical oxygen demand (COD), which makes it problematic to dispose of. Biological treatment processes have shown great success in the remediation of this water. However, these are not without their shortfalls. A variety of biological processes have been listed here as well as suggestions to improve their effectiveness. To improve the treatment efficiency, there are two main lines of thinking: First, to optimise the process through the manipulation of the physical parameters of the systems (e.g., temperature, pH, hydraulic retention time (HRT), agitation, etc.). Second, to add either pre-treatment or post-treatment processes to the main process to increase the effectiveness of the entire process overall. These different options have been discussed, with suggestions being made on the way forward.