Mar 30, 2012
Anaerobic digestion in wastewater treatmentBack
Construction|AD|Africa|Industrial|PROJECT|Resources|System|Systems|Talbot|Talbot Laboratories|Waste|Water|Africa|South Africa|Anaerobic Digestion Technology|Chemical Oxygen|Digester Treatment Systems|Energy|Large-scale Pond Systems|Product|Systems|Upstream Effluent Management|Waste|Water|Anaerobic Digestion Technology|Biofilter Technology|Process Control|Reverse Osmosis Technology|UASB Technology
© Reuse this
Water and wastewater management company Talbot & Talbot continue to successfully build and operate Upflow Anaerobic Sludge Blanket (UASB) digester treatment systems for companies throughout South Africa and Africa, across a range of industrial sectors.
“It is widely accepted that while anaerobic digestion is a proven, effective and highly efficient treatment system, upsets in performance remain common. A correctly run digester will efficiently convert up to 95% of organic material into a low-odour stabilised slurry and produce a renewable resource in the form of biogas that can be flared or used on site.
“This eliminates the need for additional solid handling and large-scale pond systems and limits reliance on nonrenewable fuels. Digester disturbances, however, continue to represent a significant risk limiting the widespread adoption of this technology,” the company highlights.
Under the Department of Water Affairs’ (DWA’s) water use licence conditions, the discharge of untreated effluent into water bodies, following reactor failure, can attract noncompliance penalties of millions of rands and, under special limit conditions, the forceful shutdown of operations for lengthy reseed periods of the digester.
Consequently, new applications are often over-engineered, under-loaded and relatively expensive.
“Despite decades of research into anaerobic digestion technology, a fundamental understanding of upstream effluent management, system sensitivity and basic process control continue to be highlighted as ongoing concerns, severely limiting the reputation and diversification of this technology,” notes Talbot & Talbot.
Digesters vary in capacity from 1 Ml/d to 5 Ml/d, treating between 1 t and 25 t of chemical oxygen demand a day, under general limit and special limit licence conditions.
The company believes that a high-performance anaerobic digester (AD) treatment system is attributed to a fully integrated approach, which begins with a systematic site water management plan and process optimisation within a client’s core business.
“Upstream focus is essential in preventing discrepancies in effluent data, which results in incorrectly designed, overloaded and poorly performing digesters; in segregating and correctly disposing of solid waste streams; and in ensuring potentially harmful contaminants are identified and isolated from the effluent system,” it states.
Plant design and construction is offered on a full turnkey basis, in addition to a full aftercare service through Talbot Operations, a business division of Talbot & Talbot.
This includes operator training, performance review and compliance monitoring on a support basis, as well as a dedicated team of competent operations and maintenance personnel on a fully outsourced basis.
“In addition, effluent sampling schedules are implemented through Talbot Laboratories to rapidly identify changes in effluent quality and monitor final discharge compliance. This guarantees the long-term treatment potential of UASB technology and a full commitment to the industry, which cannot be achieved on a build-only basis,” the company says.
A well-managed, high-performance AD system provides clients with the opportunity to recover water and energy resources from their effluent.
Secondary treatment systems in the form of activated sludge, sequential batch reactor and biofilter technology provide good-quality effluent treatment options, while water reclamation can be incorporated by ultrafiltration and reverse osmosis technology.
More recently, Talbot & Talbot have successfully designed and commissioned biogas recovery systems that capture the by-product of digestion, methane, as a renewable, carbon dioxide-energy source.
A 25 t digester with a biogas production of 6 500 Nm³/d can typically produce 52 t/d of steam, which supplements nonrenewable energy use by up to 15%.
“The realised value of a biogas recovery project (BRP) can be directly comparable to the cost of the fuel it replaces, the logistical cost of supplying fuel to remote locations and the availability of electricity throughout Africa.
Despite these benefits, Talbot & Talbot state that the real value of BRPs is the renewed interest in AD technology, a deeper understanding of good effluent handling practises and an ongoing commitment to ensuring anaerobic digesters reach their full treatment potential.
Edited by: Chanel de Bruyn© Reuse this Comment Guidelines (150 word limit)
Other Environment News
Recent Research Reports
Road and Rail 2014: A review of South Africa's road and rail infrastructure (PDF report)
Creamer Media’s Road and Rail 2014 report examines South Africa’s road and rail transport system, with particular focus on the size and state of the country’s road and rail network, the funding and maintenance of these respective networks, and the push to move...
Real Economy Year Book 2014 (PDF Report)
This edition drills down into the performance and outlook for a variety of sectors, including automotive, construction, electricity, transport, steel, water, coal, gold, iron-ore and platinum.
Real Economy Insight: Automotive 2014 (PDF Report)
This four-page brief covers key developments in the automotive industry over the past 12 months, including an overview of South Africa’s automotive market, trade figures, production and the policies influencing the sector.
Real Economy Insight: Construction 2014 (PDF Report)
This five-page brief covers key developments in the construction industry over the past 12 months. It provides an overview of the sector and includes details of employment in the sector, infrastructure and municipal spending, as well as insight into companies’...
Real Economy Insight: Electricity 2014 (PDF Report)
This five-page brief covers key developments in the electricity industry over the past 12 months, including details of State-owned power utility Eskom’s generation activities, funding and tariffs, independent power producers and prospects for the sector.
Real Economy Insight: Road and Rail 2014 (PDF Report)
This six-page brief covers key developments in the road and rail industries over the past 12 months, including details of South Africa’s road and rail network and prospects for both sectors.
This Week's Magazine
South African State-owned defence industrial group Denel has announced its fourth consecutive year of profits. The group's results for the financial year 2013/2014 were recently announced at its head office in Centurion, south of Pretoria. Revenues grew by 17%, net...
There is little opportunity for JSE-listed infrastructure company Group Five to grow shareholder value in the domestic market, says CEO Mike Upton. He says value can still be found in the private sector, in the renewable and industrial power sector, as well as in...
The National Association of Automobile Manufacturers of South Africa (Naamsa) has announced the event dates of the 2015 Johannesburg International Motor Show (JIMS). The event will take place from October 14 to October 25, 2015, at the Johannesburg Expo Centre, Nasrec.
UK engineering support services provider Babcock is set to deliver the largest order of global truck manufacturer DAF’s truck tractors in Southern Africa to bulk carrier road-based logistics company Ngululu Bulk Carriers (NBC), with 133 trucks to be delivered in...
Digital radio communications in the African local government space can open up the world, but have many challenges to overcome, notes integration and migration of legacy radio communications infrastructure with digital mobile radio company Emcom Wireless head of...