Sustainability is at the core of all operations in the Woodlands Dairy milk processing plant in Humansdorp, South Africa. Determined to minimize the use of resources and eliminate waste, Woodlands Dairy also aims for a smaller carbon footprint by lowering its energy consumption. Because a growing dairy business will produce a growing wastewater stream, Woodlands Dairy decided on an anaerobic membrane bioreactor (MBR) installation to treat it in the most efficient manner possible today, and produce energy at the same time.
Woodlands wants to take full responsibility for the environmental impact of its operations. The farming methods should not only have a minimal impact on the environment, but should also be animal-friendly and boost public support for dairy farming.
In 2012, the company adopted an environmental management system (EMS) to improve its energy efficiency and waste management, and to decrease both its emissions and use of natural resources.
The most significant risks identified as part of the EMS process included the liquid effluent management, waste management and recycling, as well as water consumption. Recycling water with an on-site wastewater treatment plant was assessed to be the most pressing concern. As part of improving its water balance, Woodlands Dairy commissioned a Memthane® system in March 2017. Around 60 percent of the dairy plant’s wastewater is now being recycled. This not only means a considerable decrease in effluent discharge but, perhaps even more importantly in an arid climate with increasingly scarce reserves, also a 60 percent decrease in the demand for fresh water.
Memthane® is an anaerobic membrane bioreactor (AnMBR) process which contains the micro biological anaerobic process (excludes oxygen), this technology turns medium to high-strength wastewater into energy and clean water that can be directly reused or discharged. The system was developed in cooperation between Veolia subsidiary Biothane and Pentair. The Biothane reactor processes the wastewater and generates biogas. Pentair’s X-Flow membranes separate the sludge and produce clean water. The sludge from the reactor remains rich in nutrients and can be used by local farmers as fertiliser.
Woodlands Dairy calls its new Memthane installation a Resource Recovery Plant (RRP). Whereas all effluent from the various production processes used to end up in a combined effluent sump, the new wastewater plant is capable of processing 1.5 MLD. At a later stage, this is set to be upgraded to 2 MLD. The incoming feed stream with about 10,000 ppm of COD is turned into a high-quality effluent with less than 100 ppm. As dairy processing is an energy-intensive operation, the biogas is a welcome bonus used to heat the on-site biogas boiler. The pretreatment of the feed stream is limited to pH adjustment and an equalisation tank. In peak season the plant can handle 1,500 m3 of wastewater containing about 12 tonnes of COD. The ultrafiltration (UF) part of the plant consists of four separate skids with 26 modules each, applying Helix membranes to maximize UF efficiency. All of this water is reused.
The anaerobic MBR significantly reduces wastewater treatment costs compared to conventional technologies. The pore size of the membranes delivers a permeate free of suspended solids. By helping to comply with legislation, protect the environment, and reduce dependence on fossil fuels, it delivers important contributions to achieving the environmental and business goals.