On the independence of hydrogen production from methanogenic suppressor in olive mill wastewater

Anaerobic degradation of olive mill wastewater (OMW) at concentrations ranging from 2 to 100 g/L of chemical oxygen demand (COD) was assessed in batch assays. Methane was the main final product obtained for the lower concentrations tested. For 25 g COD/L, H2 was temporarily produced, albeit H2 depletion occurred, likely due to homoacetogenesis, since acetate was formed concomitantly. Hydrogen was produced and accumulated permanently in the assays containing 50 g COD/L of OMW. Methanogenesis and homoacetogenesis were naturally inhibited, suggesting that hydrogen recovery from OMW can be performed without the addition of methanogenic suppressors such as 2-bromoethanosulfonate. This fact opens new perspectives for the utilization of high OMW concentrations in a two-stage valorisation process combining biohydrogen and biomethane production.The authors thank the FCT Strategic Project PEst-OE/EQB/LA0023/2013, the FCT Project RECI/BBB-EBI/0179/2012, the Project "BioEnv - Biotechnology and Bioengineering for a sustainable world", REF. NORTE-07-0124-FEDER-000048, co-funded by the Programa Operacional Regional do Norte (ON.2 - O Novo Norte), QREN, FEDER. Also through the project PTDC/ENR/69755/2006 and grants given to Marta Goncalves SFRH/BD/40746/2007, Jose Carlos Costa SFRH/BDP/48962/2008 and Angela A Abreu SFRH/BPD/82000/2011

Numerical and Experimental Analysis on the Effects of Turbocharged Compressed Bio- Methane Fuelled Automotive Spark-Ignition Engine

Abstract The implementation of recent emission norms has caused the automotive industries to develop advanced technologies for gaseous fuelled SI engines. This research focused on the comparison of turbocharged Compression Ratio (CR) 10.5:1 and naturally aspirated (NA) 12.5:1 for Compressed Bio-Methane (CBM) fuelled SI engine. The original port fuel injected automotive Compressed Natural Gas (CNG) Spark Ignition (SI) engine with 15.5 kW at 3400 rpm was made to function with CBM fuel under full throttle conditions at given CR. Also, two turbochargers T1 and T2 were analysed and validated using ANSYS turbo-machinery numerical package. T1 generated a higher-pressure ratio than T2 and was preferable. The simulation study outcomes infer that entropy generation for T1 at a 1.3 bar is less than 1.5 bar gave a better transient response. The experimental comparison was made between CR of 10.5:1 turbocharged and naturally aspirated CR of 12.5:1. At CR of 10.5:1, 1.3 bar boost pressure, brake power increased by 19.3%, reduced fuel consumption by 10.1%, and reduced hydro carbon (HC) and Carbon monoxide (CO) emissions 42.9% and 38.3%, when compared to NA CR of 12.5:1. On the whole, the downsized CR of 10.5:1 turbocharging exhibit better performance and reduced thermal loading when compared to higher CR of 12.5:1.</jats:p