To investigate the effect of control parameters (moisture, aeration and C/N ratio) on the composting evolution (temperature, pH, O₂ and volatile compounds (VCs)) of municipal solid waste and pine trimmings, a central composite experimental design was used. The ANFIS modelling obtained shows that all the independent parameters were clearly influenced by the studied parameters. The relative influence of the other independent variables on temperature was C/N > moisture > aeration. However, for pH, O₂ and VCs followed the order C/N > aeration > moisture. Moreover, the results were concordant, with a positive relation between temperature and VCs. In this way, lower VCs contents in ambient atmosphere have been found by using medium-to-high aeration (< 0.1 l_air kg⁻¹ min⁻¹), medium-to-high C/N (60–77) and high moisture (> 55%).

10 pages, 9 figures, 3 tables, 45 references.In this study, a biofiltration system was designed using mature composts of municipal solid waste (MSW) or MSW mixed with pruning residues (MSW-P) as packing materials to treat vapours of α-pinene (a dominant volatile organic compounds (VOC) emitted during the MSW-P co-composting). Monitoring the efficiency of the biofiltration system was carried out using a photoionization analyser, a commercial electronic nose (e-nose) and gas chromatography - mass spectrometry (GC/MS). Using an EBRT of 66. s, removal efficiencies for both kinds of biofilters were greater than 90% removal at different stages of the experiment. The acclimatisation periods were 10 and 25. days for the MSW biofilter and MSW-P biofilter, respectively. Removal efficiency of the system was strongly dependent upon the moisture content of the packing materials. As moisture content in the biofilters fell to below 66% for the MSW and 51% (dry basis) for MSW-P, the removal efficiency decreased to less than 90%. E-nose and GC/MS data indicate a complete degradation of the α-pinene. The e-nose detected a characteristical background emission (odour fingerprint) of each type of biofilter. Results suggest that e-nose's will become a more powerful tool for monitoring VOCs in biofiltration and composting processes in the future.This work was carried out within the project CTM2007-62117/\ud TECNO, financially supported by the CICYT (Science, technology\ud Inter Ministerial commission, Spanish Government-co-financed\ud FEDER). Cabeza I.O. held a CSIC-JAE PreDoc PhD scholarship funded\ud by the European Social Fund (ESR) and the Spanish Ministry of\ud Economy and Competiveness.Peer Reviewe

Anaerobic digestion is a suitable technology to treat cheese whey (CW), a high-strength wastewater from cheesemaking. However, CW anaerobic digestion is limited by its high biodegradability, acidic pH, and lack of alkalinity. This publication evaluated the acidification risk of CW anaerobic digestion under psychrophilic and mesophilic conditions, aiming to improve digester design, operation, and decision-making when facing instability periods. To evaluate the acidification risk of CW anaerobic digestion, biochemical methane potential (BMP) tests were carried out at four different organic loads, each under psychrophilic (20 °C) and mesophilic (35 °C) conditions. Besides methane production, pH, soluble chemical oxygen demand, volatile fatty acid and alcohols were also monitored. Experimental results showed that CW can be successfully degraded under both temperature conditions, with methane yields of 389–436 mLCH₄/gVS. The organic load had a greater impact on the accumulation of intermediate products than temperature, indicating that process inhibition by overloading is plausible under psychrophilic and mesophilic conditions. However, the degradation rate under mesophilic conditions was faster than under psychrophilic conditions. Experimental results also revealed a higher imbalance between fermentation and methanogenesis rate under psychrophilic conditions, which resulted in higher concentrations of intermediate products (volatile fatty acids and alcohols) and prolonged lower pHs. These results indicate that the degradation of intermediate products is less favourable under psychrophilic conditions compared to mesophilic conditions. This implies that psychrophilic digesters have a lower capacity to recover from process disturbances, increasing the risk of process underperformance or even failure under psychrophilic conditions.