Anaerobic Digestion (AD)

ORA has longstanding experience and a wealth of expertise which enable us to provide a broad range of services in support of AD. With our partners, ORA has been involved in the development and optimisation of numerous AD facilities both in the UK and Europe.

Anaerobic Digestion due diligence
Anaerobic Digestion tanks

Feasibility studies

ORA has extensive experience in the design of AD facilities. This has involved co-ordination with technology suppliers and design integration for the creation of a cohesive and functional process through to a complete design service starting with mass balances, process design and site layout.

Obtaining planning consent is a key issue to be addressed when developing an AD facility. ORA is able to assist clients by gathering and presenting the technical information required by planning authorities prior to submitting a planning application. ORA is also able to provide technical support to resolve planning issues.

ORA is able to create projected capital and operating costings for specific situations, and model different financial circumstances. Our objective advice is used by financial institutions and investors who might be considering the suitability of a given operation for financial backing.

Mass flows and BMW balance determination

The economics of an AD process will be determined by the processing of materials into the most viable products. Compliance requirements with NI and LATS targets can be compared with plant mass and BMW balances to ensure that ultimate plant performance will be within the required output specifications.

Legislative and environmental compliance

The AD industry is controlled by a number of different pieces of legislation. ORA keeps abreast of changes in legislation, providing consultation back to DEFRA and has sat on expert panels to discuss how regulations such as the ABPR are to be implemented. We are therefore in a very strong position to advise clients on regulatory compliance and to enable swift resolution of queries.

Anaerobic digestion construction management
Dewatering press

The environmental impact of AD is becoming a key issue. An environmental impact assessment may be required or may be thought prudent. ORA is able to provide baseline environmental audits looking at specific operations and to report on the existing or potential impact that AD might have. In some situations where problems have occurred or where sites are in particularly sensitive areas, environmental monitoring for parameters such as odour, bioaerosols and leachate may be needed. ORA is able to offer this service tailored to suit a clients needs.

ORA works closely with the Environment Agency. With our contacts, ORA is in a strong position to assist clients with gathering the information needed to apply for the necessary permissions to operate an AD plant, to assist with completing the necessary application forms and to provide technical support and liaison between operators and Environment Agency staff.

Management and support of the tendering process

Where it is crucial for the best service to be obtained at the best price, both local authorities and private companies are making increasing use of tendering procedures for selection of contractors. A key part of this process is the development of comprehensive, unambiguous and concise tender documents. ORA has extensive experience in the development of such documents and have particular skills in drafting technical specifications. When a tendering process is underway, there is often a need for objective technical appraisal of submitted tenders. ORA has worked with both public and private bodies in this capacity, reviewing tenders, and reporting on a wide range of technical issues.

Design and construction management

Effective project management ensures the smooth implementation of any project. ORA has experience in both the public and private sectors of managing anaerobic digestion projects to ensure best value for money is obtained. The whole process can be covered from initial concept through to financial close, including design, manufacturing, construction, commissioning and handover.

With the high cost of land in the UK, efficient site design is crucial for cost effective anaerobic digestion operations. ORA is able to provide a site design service for both small and large scale facilities and can tailor the service to suit the clients needs in terms of detail required.

Operating in compliance with legislation
Stack emissions monitoring

Process testing and optimisation

Independent process auditing, whether theoretical or physical, is a key component of a facility's development. ORA has experience in both types of process audits on large and small scale facilities.

With existing operations, there is sometimes a need to bring in additional expertise to help solve problems and provide objectivity. This service can be tailored to suit a client’s specific needs – either by providing a ‘one off’ solution or by offering ongoing support to monitor and optimise a situation over time.

Quality assurance

ORA is an approved consultant under the Organics Recycling Group (ORG) approved consultants scheme. We are able to offer assistance in understanding and gaining accreditation for the PAS 110 specification for digestate. We are also experienced with other quality standards such as those under which organic farmers and growers operate and can provide advice on specific quality issues where needed. ORA has undertaken a number of market assessments for different end products and is also able to run container and field based growing trials to demonstrate product quality and enhance product credibility.

Product and market identification

In terms of quality assurance, ORA is experienced in the sampling and analysis procedures required to obtain representative samples from the outputs of an AD facility. We are therefore able to provide independent assurance that a product meets the required specification.

The markets for end products are critical in making a project bankable and in some instances the lack of a potential market can be a ‘deal breaker’. ORA is experienced in undertaking market assessments for different end products and are able to assist clients in identifying potential end markets for their products. This is usually a bespoke service tailored to fit a client’s particular need.


With existing operations, there is sometimes a need to bring in additional expertise to help sort out problems. ORA has extensive experience in resolving problems or providing independent assessments of situations where objectivity is needed.

Process auditing can be carried out either on a theoretical basis or by physically auditing an existing operation. It involves looking at what a technology supplier or operator predicts they are able do. For example, given throughputs, waste separation details and quality of end product, and looking at the process in plan form or on the ground, ORA are able to assess whether or not they will be actually achievable.

Anaerobic Digestion Projects

Please click here to view case studies which involve anaerobic digestion.