A proposal based on Bioconservacion’s technology was selected as the winning bid in the public tender released in 2015, covering the design, procurement and construction of a biogas desulfurizing unit to be installed in the waste water treatment plant in Chania, Greece.
With a population over 100,000, Chania is the second largest municipality in the Greek island of Crete. Its waste water treatment plant is composed of primary and secondary settlers, two biological reactors and four anaerobic digesters to produce biogas.
The WWTP facility has been designed to optimize energy integration by using the combustion of the produced biogas in a CHP (combined heat and power) engine. The heat produced by the engine is used to both pre-heat the sludge in the digesters and to dry the outcoming digestate. This measures assure maximum energy efficiency but they require proper purification of the biogas to protect the internal combustion engines. Particularly, the concentration of H2S needs to be reduced from 2000 ppm down to virtually zero to protect metal parts from corrosion, hence maximizing engine operation life.
The solution designed by Bioconservacion was proposed in partnership with the Greek engineering firm DIMTECH, and it was chosen by the management of the WWTP at Chania because of its superior advantages over other currently available biogas desulphurization equipment, namely:
- Extremely high adsorption capacity for H2S: 45% in weight (over 10 cycles).
- Ultra-low pressure drop across the fixed beds.
- Excellent performance even in the absence of O2.
- Moderate amounts of volatile organic compounds and CO2 do not affect the optimum functioning of the product.
- Easily regenerable up to 10 times by simply blowing ambient air through the beds.
- Extremely low maintenance requirements.
The unit is composed of two fixed beds mounted in parallel and configured to work with the highly efficient Bi-On Sigmaproprietary filtration media in an totally autonomous and completely safe way.
An integrated machine type PLC, handling over 30 i/o control signals, allows for fully automated operation in all working modes (operation, inertization, regeneration and stop/bypass). Command input is conducted from a locally mounted 10” touch screen and surveillance can also be performed remotely, from an office PC or even from thousands of kilometers away, thanks to an internet port directly built on the PLC. This feature was extensively used by Bioconservacion engineers during the evaluation period.
The plant started operation beginning of 2016 and the performance evaluation tests lasted 6 months. At the end of this time, a delegate team from Bioconservacion performed the final commissioning and the plant was officially put to service and satisfactorily delivered to the client.
With the same technology and start-up method, this excellent results can be obtained for any application requiring biogas purification (landfill and anaerobic digestion biogas combustion, CHP, biogas concentration and injection of bio-methane into the grid), and the final performance of the system can be guaranteed.