GENeco – Avoiding landfill and generating compost

In the run up to this years Green Apple Awards at the Houses of Parliament on the 12th November, we will be reviewing some of the amazing award winning projects from last year.

GENeco is Wessex Water’s waste to energy company that recycles waste, produces renewable energy and provides the agricultural industry with a nutrient-rich fertiliser.

As part of our sustainability vision we aim to avoid the generation of waste and where produced, to manage it effectively and responsibly through reuse and recycling activities.

As part of the sewage treatment process, we screen out from the sewage all material that is detrimental to the treatment system. This amounts to some 5,500 tonnes per year of grit, sand, rags, plastics and other items such as nappies, which, due to the nature of the material, have historically had to be disposed of to landfill.

Keen to find an acceptable and more sustainable alternative, we decided to trial a different treatment method to treat the waste, to not only minimise the waste sent to landfill, but to also explore other opportunities for recycling.

Landfill costs £108 per tonne, increasing by £8 per tonne per year, so the solution could also help reduce our landfill costs.

The treatment method trialled uses similar processes to composting and use of this term in this article aids explanation. However, due to the presence of some non- biodegradable materials it cannot currently be specifically classed as composting.

WHAT DID THE PROJECT INVOLVE DOING AND WHY DID YOU DO IT?

Staff carried out initial trials composting the grit and screenings from our Bristol sewage treatment works in different combinations:

● Separately on their own

● Separately with straw

● Both mixed with straw, and with differing amounts of straw for aeration and carbon supply.

The materials composted best with the grit and screenings mixed together, with no straw added, with the compost piles turned weekly. The composting heaps achieved 70 degrees centigrade within four to five days and retained temperature above 45 degrees for several months. This is important to deliver a reliable treatment process, giving good pathogen removal and stabilisation, such as low odour in the final product.

The final product has been accepted as giving agricultural benefit and the Environment Agency (EA) has agreed it can be recycled direct to agricultural land and restoration. It has been used as fertiliser in Somerset and soil conditioner in Dorset.

WHO AND WHAT HAS BENEFITED?

Treating the material in this way was a UK first, with other companies not expecting it to work. Additionally, close work with the Environment Agency allowed the material to be used for land recycling and reclamation.

It has meant we have been able to reduce waste as the compost process reduces the amount of material to be disposed of. Importantly, we have also diverted this waste from landfill.

The process is now being extended to cover waste from other sewerage and sewage treatment activities. For further details on the GENeco food waste plant please visit www.geneco.uk.com or contact us on 01225 524 560.

A state of the art food waste processing facility that will have the capacity to receive up to 40,000 tonnes of food waste per year is being built by GENeco at the Bristol sewage treatment works in Avonmouth.

GENeco’s food waste anaerobic digestion (AD) plant will transform food waste into renewable energy and nutrient rich fertiliser. At full capacity the plant will be capable of supplying the needs for more than 2,500 homes.

This exciting new development will be the first large scale food waste AD plant in the Bristol and surrounding area. It will offer supermarkets, local authorities, food manufacturing organisations, hospitals, universities, catering establishments and waste management companies a cost effective and sustainable local solution for treating their packaged and unpackaged food waste.

The plant will be open in autumn 2012 it will offer organisations in and around the Bristol area with a cost effective and sustainable local solution for diverting their food waste from landfill.