Anaerobic digestion and the dairy industry

The UK loses around 330,000 tonnes of milk each year, according to the Waste and Resources Action Programme (WRAP). The biggest culprit for dairy waste generation is consumers. According to WRAP, homes generate nearly 90% of the total milk waste in the country – around 290,000 tonnes

Retailers and transportation are the next biggest ‘wasters’ of milk, wasting around 30,000 tonnes in leaks and breakages and finally, processing generates around 13,000 tonnes of dairy waste. In monetary terms, the loss equates to more than £150 million (€171.5m). But in addition to the financial loss, milk waste also impacts the environment, both as one of the biggest producers of greenhouse gases as well as a hazard to aquatic life.

There is no doubt, therefore, that how dairy waste is managed is essential at every step of the dairy supply chain, from the farms through the logistics and supply chain, to the retailers and, eventually, the consumers. As with all waste products, it helps to think of ways to reuse milk waste before it is discarded. But can dairy waste be turned into a reusable resource?

Even with every precaution, some amount of dairy waste is inevitable. However, waste generated on farms, during processing or further down the chain, including from the food and hospitality industry, needs to be handled and disposed of responsibly. Thankfully, there is a process that supports the industry to reduce waste in a sustainable way, notes Chris Mallia, sales manager at BioteCH4, an anaerobic digestion company in the UK. 

Anaerobic digestion (AD) is the sustainable process of recycling large amounts of food waste and animal waste into green energy and biofertiliser, a nutrient-rich organic material used to fertilise farmland. Dairy waste can benefit from this process, the waste enters a building where it is processed into a liquid porridge, and then pumped into the anaerobic digestion plant. It is here that bacteria feed on the food waste, breaking it down to produce biogas. The biogas is captured and used as a fuel in combined heat and power (CHP) engines or cleaned and sent directly to the gas grid. The waste is pasteurised to ensure that any pathogens are destroyed and the biofertiliser (digestate) is stored in large lagoons, ready to be applied on farmland when the crops require it.

There are several benefits. First, It’s eco-friendly. For a business, recycling your dairy waste via anaerobic digestion helps reduce the number of greenhouse gases it would release compared with land spreading. Next, it’s a renewable form of energy. The biogas created from AD is rich in methane and can be converted into renewable energy (gas or electricity), or into use as a vehicle fuel. The vehicles that tip at our sites could then fill up on gas or electricity that we generate onsite, which would power their vehicle for the onward journey.

There are also economic opportunities. It’s a low-cost process which is not weather dependent and is available 365 days a year, unlike land spreading. Creating organic fertiliser for farmers. With an increased focus on proving environmental benefit from landspreading, converting dairy waste into a high nutrient biofertiliser prior to spreading ensures a closed loop of carbon and energy capture.

However, dairy products are strictly regulated animal by-products. As a result, not everyone can process all dairy waste and so working with AD operators who are ABP registered is a must. Nevertheless, for those that can, turning to AD for dairy waste may be the best solution to the waste disposal question and a positive step towards being more environmentally responsible.

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