A High Rate Anaerobic Digestion Plant can treat high strength Wastewater Effluent Streams including sewage sludge, very efficiently. This is an important finding due to the fact that biodegradable wastewaters contribute about 6% of all anthropogenic methane emissions.
High-rate anaerobic digesters have the potential to treat such wastewaters while also creating renewable energy. This energy is obtained from the purified biogas, making it possible to capture of methane for usage as a relatively clean power resource.
Comparison of Common Biogas Technologies
The original Press Release below marked the start of work on an early UK “high-rate” AD plant:
BioWayste’s £2M High Rate Anaerobic Digestion Plant to Treat Brocklesby Ltd Effluent Streams [Press Release – June 2013]
Update to the Original Post published in June 2013 – BioWayste failed as a company in 2014, and was wound-up, but the £2 million High Rate Anaerobic Digestion Plant to Treat Brocklesby Ltd Effluent Streams was completed. We understand that it continues to operate with an increasing demand for the fuel it produces.
BioWayste and Brocklesby Ltd of North Cave near Hull, are delighted to announce the signing of a Build Own and Operate contract for 6 years to provide green electricity and heat from BioWayste’s £2M high rate anaerobic digestion process technology.
In a landmark move, Brocklesby Ltd. have chosen BioWayste as its exclusive partner to run and manage the 40,000 ton p.a. AD Plant on its 7 acre site.
Six of BioWayste’s high rate reactors along with CHP engines will provide Brocklesby with 75% of its current electricity usage, all generated from waste products currently being tankered from site.
The BioWayste plant will make green energy by treating the waste on site using their high rate anaerobic digestion process. They will be disposing of a clean effluent via Yorkshire Water’s infrastructure.
High Rate Anaerobic Digestion Process to Provide Green Electricity and Heat in 6 Year Contract
Rob Brocklesby, Managing Director, said:
“It makes great sense for Brocklesby to continue the process of recycling already at the North Cave Plant with BioWayste AD technology. Not only are we removing tankers from the local road infrastructure we are reducing Brocklesby Ltd’s reliance on fossil fuels by making green energy from waste on our own site. Brocklesby have invested heavily in the North Cave plant over recent years, creating many local jobs. The BioWayste plant will help our carbon reduction programme and will provide more local employment opportunities. This high rate anaerobic digestion process plant will also save us money and give us long term, sustainable green energy”.
The BioWayste plant will be owned, financed and operated by BioWayste thereby allowing Brocklesby to receive a secure green energy supply from its waste. It will do this without the need to diversify from their core business. The BioWayste AD plants are small footprint installations and this one fits easily into the corner of the ever-expanding Brocklesby site.
As the technology is a modular system of high rate reactors with the ability to expand the plant. This means that alongside the Brocklesby business model, BioWayste will work to service the current effluent stream. In the future they will be able to grow in accordance with Brocklesby’s aspirations.
All of the BioWayste technology is pre-fabricated and arrives on site ready for plug & play installation, further increasing the sustainability of the total solution. Their high rate anaerobic digestion process design also reduces installation time thereby giving Brocklesby larger savings with early green electricity production.
Long Term Cost Benefits to Brocklesby – Secured Through Use of High Rate Anaerobic Digestion Process
David Orme, Sales Manager for BioWayste commented:
“BioWayste are delighted to be working with Brocklesby on this project. The Brocklesby team have chosen BioWayste for a six year partnership to make green electricity and heat from their final effluent waste. Working with other partners including the Environment Agency and Yorkshire Water, we aim to provide a fully automated and controlled service to Brocklesby using locally recruited trained operatives and management. Like Brocklesby we are committed to clean, green and sustainable energy whilst minimising the impact on the site concerned. Using AD to treat Brocklesby’s effluent stream compliments Brocklesby’s existing business model, recycling and re-using food waste products from across the UK. The main Brocklesby Plant will now be able to use green energy to assist in their already sustainable business further reducing their carbon footprint. This is excellent for both the environment and local infrastructure, giving long term cost benefits to Brocklesby without the need for them to have a further process to manage. A genuine win/win situation”.
Both Brocklesby and BioWayste assist a large number of food and beverage companies with their waste management. This high rate anaerobic digestion process plant will ensure that many of Brocklesby’s clients will know that the final destination for their waste will be in green electricity production and will only add to their whole food chain sustainability credentials.
More About High Rate Anaerobic Digestion (HRAD)
The term high rate anaerobic digestion relates to Solids and Hydraulic Retention Times (SRT and HRT) for the reactor. SRT and HRT are the average time solids and liquids are held in the digestion process. Anaerobic reactions (hydrolysis, fermentation and methanogenesis) and anaerobic reactor size are directly related to these parameters.
Each of the anaerobic digestion reactions requires a minimum SRT to be completed and if the design SRT is less, than that the digestion process will fail (Metcalf and Eddy, 2003).
In a completely mixed reactor with no recycle, solids and hydraulic retention times are the same.
In practice, for high rate digestion the values of SRT range between 10 to 20 days (Metcalf and Eddy, 2003). via www.theecoambassador.com
(HRAD) of wastewater separated from grease trap waste
In a study reported in Renewable Energy, (Volume 62, February 2014, Pages 234-242), the co-production of biodiesel and methane gas from grease trap waste (GTW) was evaluated.
The GTW was first processed into two separate phases comprised of fats, oil, and grease (FOG) and high strength wastewater (GTW wastewater).
The GTW wastewater was then anaerobically digested in biochar packed up-flow column reactors to produce methane gas and a low-strength wastewater effluent while the FOG phase was set aside for conversion into biodiesel.
Anaerobic digestion efficiencies that yielded chemical oxygen demand (COD) reductions up to 95% and methane head-space concentrations between 60 and 80% were achieved along with FOG to biodiesel conversion efficiencies of 90%.
The results were very good. Methane production yields (m3 per kg COD reduced) reached theoretical maximums, with near total depletion of the volatile organic acids. via Sciencedirect.com