Fixed Gas Detection System Combines Worldwide Approvals with SIL 2 Capability

To check sewage sludge AD, Southern Water in UK & Celtic Anglian Water (CAW) in Dublin, Waterford and Sligo use Geotech Biogas Check portable biogas analysers specially developed for AD biogas and based on proven methane and associated biogas analysis equipment.

Southern Water has an important routine; every day it checks the health of its sewage sludge anaerobic digesters on eighteen sites. There, Southern Water treats and recycles 1,400 million litres of wastewater each day from nearly two million households. With that huge responsibility this utility company, like any other, needs to ensure the security of its sewage sludge digesters working at their optimum. Central to achieving that is Southern Water’s ‘Best Practice for the Operation of Sludge Digesters’. This it produced to ensure industry best practice operating routines are carried out at each site. They include daily analysis of pH/alkalinity, volatile fatty acids (VFAs) and biogas composition.

For biogas analysis Southern Water uses fourteen Geotech Biogas Check portable biogas analysers. They measure methane (CH4), hydrogen sulphide (H2S), oxygen (02) and carbon dioxide (CO2) – as the balance gas. Southern Water checks each digester is healthy, producing over sixty percent CH4, the minimum for its CHP engines to run and generate electricity. The CHPs have a 1000ppm maximum for H2S. Above that, H2S may damage CHP engines.

Southern Water selected the simple-to-operate Biogas Check for anaerobic digester biogas gas analysis for which it was designed.

Successful Sludge AD at Ringsend in Dublin

Celtic Anglian Water (CAW) Ringsend treatment works, Dublin, one of the most advanced wastewater treatment plants in the world, monitors sludge AD gases daily. They use a Geotech Biogas Check portable gas analyser to monitor CH4, CO2, O2, H2S and hydrogen (H2). These can indicate change and help optimise gas production and digester stability. To check hydrogen sulphide (H2S) and hydrogen (H2), CAW uses gas-specific electrochemical cell ‘pods’ for each gas.

CAW operates Ireland’s largest wastewater treatment plant at Ringsend and has large wastewater treatment plants in Waterford and Sligo where the Biogas Check is also used. The Ringsend treatment works caters for a population of 1.7 million people. Ringsend AD converts some fifty percent of sludge volatile solids into some 35,000 m3/day of biogas from the three digesters.

Tried & Tested
Geotech uses tried, tested and proven components in its gas analysers – in use in demanding conditions on biogas AD and landfill sites around the world daily. ATEX certified for use in potentially explosive atmospheres, the field-proven technology enables consistent collection of data for improved analysis and accurate reporting. One key Geotech design standard was that, ‘Anyone can pick up a Biogas Check and use it without opening the manual’. They can and they do, globally because keeping sludge AD working is the same objective for all operators. More: Tel: +44 (0)1926 338111

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