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This paper investigates the influence of thermal pretreatment on kinetic parameters based on four kinetic models: Modified Gompertz, transference and logistic functions and first order equation. The kinetic modeling was applied on experimental results of previous study on producing methane from anaerobic digestion of Recycled Pulp and Paper Sludge (RPPS) under mesophilic conditions. We observed that the thermal pretreatment improve considerably improved the kinetic parameters mainly the methane production rate and the lag phase. Indeed, it can be noted that methane production rate μ increases significantly from a value of 4.72 to 16.27 Nml/h using logistic function for 1 g VS/L added load. Then the lag phase parameter λ has dramatically decreased from 5.46 to 1.04 h using logistic function for 1,5g VS/L added load. This means that the thermal pretreatment of RPPS accelerates the methane production process and saves time.

Coffee is present in every street in the world and is without a doubt one of the most consumed beverages. Moreover, it is the third most consumed drink in the world. Recent estimations from the International Coffee Organization put. The world coffee production at about 6 million tons per year. Its uncontrolled disposal can cause environmental problems, but if handled properly, it can be processed into pellets, and used as an energy source. In the present study, the production of energy from coffee waste (CW) is an interesting alternative to traditional production lines. The objective of this study is to calculate the energetic potential (Ep), which can be generated by anaerobic digestion (AD) and thermochemical conversion (TC), of the organic fraction of CW in the city of Kenitra, Morocco. An elementary analysis allows us to estimate the calorific value by the TC. The lower and higher calorific values were estimated to be: 18.71 and 20.28 MJ/Kg, respectively. Ep results by AD and CT were 0.25 and 1.3 MWh/t, respectively. [ABSTRACT FROM AUTHOR]

Banana peel is a concentrated source of putrid organic waste; this waste is considered as a source of the energy produced by the process of anaerobic digestion. The objective of this study is the evaluation of methane production by anaerobic digestion of banana peels. The experiment was carried out under mesophilic conditions using a semi-continuous laboratory digester (1.5 L) with a constant agitation that maintains the bacterial activity in the digester and reduces the risk of sedimentation. The treated substrate is obtained from the region of ELGHARB, and it was cut and crushed to particles whose size is less than 1 cm. Throughout the period of the experiment, the pH was around neutrality, between 7.4 and 7.9. The average value of alkalinity was 1500 mg L-1 which permits the well function of the process. In addition to the control of stability parameters of the anaerobic digestion, there was also a control of the organic loading rate presented by the total solids (TS) and volatile solids (VS). A daily control of methane production shows that the methanogenic potential is 257 m³ t-1. [ABSTRACT FROM AUTHOR]

Anaerobic co-digestion of residual cabbage and cauliflower mixed at a ratio 1:1 (w/w) was investigated in two continuously stirred tank reactors under mesophilic conditions to ensure stability and enhanced methane generation. The experiments, including start-up, inoculum acclimatisation and treatment of the waste mixture, were carried out over a 65-day period. The characterisation results showed that the residual mixture contained a high proportion of total Kjeldahl nitrogen (around 37 g N/kg dry weight). The maximum value of methanogenic yield potential was found to be 250 LSTP/kg VS (volatile solid) added, at STP conditions (0°C, 1 atm), by loading organic substrate at a concentration of 1 g VS/L, while its biodegradability was 60%. However, instability of the biomethanisation process was observed after 17 days, which might be a consequence of the high concentration of nitrogen in the reactors. The evaluation of the kinetics of the valorisation process revealed that the waste mixture studied can easily be biodegraded through anaerobic co-digestion. [ABSTRACT FROM AUTHOR]

Mesophilic anaerobic digestion is a treatment that is widely applied for sewage sludge management but has several disadvantages such as low methane yield, poor biodegradability and nutrient imbalance. In this paper, we propose orange peel waste as an easily biodegradable co-substrate to improve the viability of the process. Sewage sludge and orange peel waste were mixed at a proportion of 70:30 (wet weight), respectively. The stability was maintained within correct parameters throughout the process, while the methane yield coefficient and biodegradability were 165 L/kg volatile solids (VS) (0°C, 1 atm) and 76% (VS), respectively. The organic loading rate (OLR) increased from 0.4 to 1.6 kg VS/m3 d. Nevertheless, the OLR and methane production rate decreased at the highest loads, suggesting the occurrence of an inhibition phenomenon. [ABSTRACT FROM AUTHOR]