Maurizio Rosso

Investigation of increasing organic loading rate in the co-digestion of energy crops and cow manure mix.

The increase of the organic loading rate from 4.45 to 7.78 g-VS/l-d in a one stage, pilot biogas plant was investigated. The experiment was conducted using a co-digestion of cow manure and crop silage mix. The test was divided in three subsequent phases with different feeding ratios. The benefits of optimizing the proportion of crops and loading rate in co-digestion were shown by the fact that during feeding with 70% VS of crop in the feedstock, up to 109% higher specific methane yield was obtained than during the start up phase (only manure). It was also found that further increasing the proportion of crop silage up (to 80%) led to a process breakdown with a decrease of methane proportion down to 48%. On the basis of the present results, it could be possible to obtain an electricity production equal to 15 kwh per 1 t/d. At the end of the monitoring biogas yield was equal to 237 and 249l-CH(4)/kg-VS in the first two phases, and to 61.6l-CH(4)/kg-VS in the third one that led to a process breakdown. The result of this study show, that most agricultural biogas plant have a great potential for a significant capacity increase and technology improvement.

Biogas production by anaerobic co-digestion of cattle slurry and cheese whey

Biogas yield of mixtures of cattle slurry and cheese whey, rates of production of methane, removal efficiencies of chemical oxygen demand (COD) and biological oxygen demand (BOD) were investigated at 35 °C. Stable biogas production of 621 l/kg volatile solids at a hydraulic retention time of 42 days in a mixture containing 50% slurry and whey was obtained. The concentration of methane in the biogas was around 55%. Maximum removal efficiencies for COD and BOD5 were 82% and 90%, respectively. A maximum biogas production increase of 79% with respect to the start-up phase was achieved. The result of this study show that co-digestion of a high volume of whey (up to 65% in volume) is possible without the use of chemicals for pH correction, but also that this kind of mix has a similar energetic potential for anaerobic digestion as energy crops such as maize.

Development of a pilot scale anaerobic digester for biogas production from cow manure and whey mix.

This paper presents results from anaerobic digestion of cow manure and whey mix. A pilot scale anaerobic digester, 128 l in volume, has been developed, to operate under batch and fed-batch conditions. The versatile and unique characteristics of the instrument allowed testing the methane production directly in the farm. The digester performance was evaluated with two calibration tests, the main for a period of 56 days. The study test was divided into three phases, one for each type of feeding operation (batch, fed-batch, batch). The initial phase of digestion resulted in 57 l-CH(4)/kg-VS, the second phase had a yield of 86.6 l-CH(4)/kg-VS and the third one had a production of 67 l-CH(4)/kg-VS. The total methane yield was equal to 211.4 l-CH(4)/kg-VS. Using the obtained pilot plant results to a real scale diary production cycle, it was possible to evaluate an electricity production equal to 8.86 kwh per 1 t/d. The conducted tests did show that there is a good potential to the use of a cow manure and whey biomass mix for biogas production.

Environmental and engineering performance assessment of biofilters and retention systems for pavement stormwater

This work is aimed at investigating the use of green infrastructure technologies for the infiltration of stormwater runoff from urban road pavements into soil, and as a means to support the evapotranspiration and harvesting processes. Porous concrete pavements and vegetated biofilters were considered to assess pollutant removal and hydraulic performances. The investigations were at bench-scale for single materials, and at column and box scale for composite structures. The pollutant reduction was determined on the basis of suspended solids, heavy metals and hydrocarbon concentration, with promising results that were found to be dependent on filter material characteristics, layer distribution, and permeability.