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Poultry litter (PL) was pre-treated in order to reduce its nitrogen content and to increase the C/N ratio. The pre-treatment consisted of a first anaerobiosis phase of about 60 days in order to accumulate ammonia nitrogen, followed by an ammonia stripping phase by heating the substrate at 80 °C for 24 h. The digestion was performed with PL and pre-treated PL (TPL) after ammonia stripping as mono-substrate under four total solids loads, i.e. 5%, 10%, 15% and 20%. The TPL after ammonia stripping displayed lower ammonia (62–73%) and VFA (41–65%) concentrations compared to digesters with raw PL, while bio-methane yield increased about 8–124%. Bio-methane yields in the series with TPL after ammonia stripping were about 193, 196, 215 and 147 L CH 4 /kg COD , based on the COD added, for 5%, 10%, 15% and 20% TS load, respectively. The results indicate that lowering nitrogen content using the suggested process improves bio-methane yields significantly. [ABSTRACT FROM AUTHOR]

Abstract: Olive mill wastewater (OMW) was digested in its original composition (100% v/v) in an anaerobic hybrid. High concentrations (54–55kg COD m−3), acid pH (5.0) and lack of alkalinity and nitrogen are some OMW adverse characteristics. Loads of 8kg COD m−3 d−1 provided 3.7–3.8m3 biogas m−3 d−1 (63–64% CH4) and 81–82% COD removal. An effluent with basic pH (8.1) and high alkalinity was obtained. A good performance was also observed with weekly load shocks (2.7–4.1, 8.4–10.4kg COD m−3 d−1) by introducing piggery effluent and OMW alternately. Biogas of 3.0–3.4m3 m−3 d−1 (63–69% CH4) was reached. Developed biomass (350days) was neither affected by raw OMW nor by organic shocks. Through the effluents complementarity concept, a stable process able of degrading the original OMW alone was obtained. Unlike what is referred, OMW is an energy resource through anaerobiosis without additional expenses to correct it or decrease its concentration/toxicity. [Copyright &y& Elsevier]

Abstract: Laboratory and pilot-scale experiments were carried out in order to evaluate the influence of thermal pre-treatment time on waste-activated sludge properties and anaerobic biodegradability. Six experimental conditions were analyzed from 0 to 30min of hydrolysis time. Solubilization of macromolecular compounds, changes in the main sludge properties and anaerobic biodegradability of the sewage sludge were evaluated. A similar carbohydrate solubilization degree was achieved, from 53% to 70% and 59% to 75% for lab- and pilot-scale experiments, respectively. In the case of proteins, the values of solubilization were lower in the pilot-scale experiment than in the laboratory, with 31–45% and 47–70%, respectively. Ammonia and volatile fatty acid did not undergo important changes; however the sludge dewaterability enhanced at increased pre-treatment times. All the pre-treatment conditions had a positive effect with regard to anaerobic biodegradability and by fitting experimental data with a simplified mathematical model, it was concluded that the maximum biogas production rate is more influenced by the pre-treatment time than the total biogas production. [ABSTRACT FROM AUTHOR]

Abstract: An anaerobic digestion technique was applied to textile dye wastewater aiming at the colour and COD removal. Pet bottles of 5L capacity were used as reactor which contains methanogenic sludge of half a liter capacity which was used for the treatment of combined synthetic textile dye and starch wastewater at different mixing ratios of 20:80, 30:70, 40:60, 50:50 and 60:40 with initial COD concentrations as 3520, 3440, 3360, 3264 and 3144mgL−1, respectively. The reactor was maintained at room temperature (30±3°C) with initial pH of 7. The maximum COD and colour removal were 81.0% and 87.3% at an optimum mixing ratio of 30:70 of textile dye and starch wastewaters. Both Monod’s and Haldane’s models were adopted in this study. The kinetic constants of cell growth under Haldane’s model were satisfactory when compared to Monod’s model. The kinetic constants obtained by Haldane’s model were found to be in the range of μ max =0.037–0.146h−1, K s =651.04–1372.88mgL−1 and K i =5681.81–18727.59mgL−1. [ABSTRACT FROM AUTHOR]