The subject of the presented paper focused on Biosolid Technologies offered by Eliquo, with specific reference to degassing for digested sludge using the ELOVAC® system and Thermal Hydrolysis Process with the LYSOTHERM® technology.

Key points of the presentation were:

CH₄ emissions from sludge treatment make up 75% of the diffuse CO₂-equivalent emissions from wastewater treatment plants¹. While CH₄ is a powerful greenhouse gas (GHG): 1 CH₄ corresponds to 28 CO₂ equivalents², CH₄ is also a highly energetic gas with a calorific value of 10 kWh/m³. As a unique technology for vacuum degassing of digested sludge, ELOVAC^®takes advantage of these two facts – it uses a vacuum pump to extract methane from the digested sludge, and in doing so, it not only withdraws soluble gas from the digested sludge, but also very small gas bubbles attached to particles. This is a major contribution to reducing greenhouse gas emissions, while providing additional gas yield to the CHP.

In addition to the environmental benefits, ELOVAC^®can also improve the dewaterability of digested sludge by up to 3%-points.

Lingen: ELOVAC^®in operation

In Lingen in Northwest Germany, a 195,000 P.E. WwTP, where a full scale ELOVAC^® unit is operating the following results have been achieved:

• At 230 millibar, 340 L of biogas per m³ of sludge can be withdrawn, resulting in ca.150 tons of CO₂-emissions avoided per year or 25% of the CO₂- equivalent emissions of the treatment plant.
• Due to better dewatering, reduction in the sludge hauling disposal by up to 15% solely by ELOVAC^®(based on TR(A) measurements).
• The overall plant optimisation project in Lingen, including the implementation of other Eliquo Technologies: LYSOTHERM^®(Unique Thermal Hydrolysis Technology with no stem and no chemicals) and EloPhos^®(controlled struvite precipitation) together with ELOVAC^®, have resulted in 484,000 €/year in operational savings and 400 tons/year of CO₂equivalent emissions avoided. The avoided emissions are approximately equivalent to 8,500-car kilometres/day – the same distance as driving from the U.K. to Japan every day!

 Eliquo is currently conducting lab tests to identify the benefits U.K. water utilities can expect with ELOVAC^®,dependent on their specific sludge characteristics. 

For further information on the Biosolids Technologies visit the Sludge Treatment section on the website, or contact Lewis O’Brien, Technical Director on 01726 861900, email send email. 

• ¹Gärtner, A.; Hirschberger, R.; Becker, A.; Düputell, D.(2017) Diffuse biogene Emissionen auf Kläranlagen (Diffuse biogenic emissions on sewage treatment plants). Korrespondenz Abwasser, Abfall, 11, 985-993
• ² IPCC (2014) Climate Change 2014: Synthesis Report, Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Core Writing Team, R.K. Pachauri and L.A. Meyer (eds.)]. IPCC, Geneva, Switzerland, 151 pp.