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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.

Solar biogas system production offers the possibility to simultaneously produce heat, electricity and to treat waste products as well as to reduce greenhouse gas emissions in the industrial sector. In this paper, we report on the development of an experimental solar biogas prototype to valorize the biomass generated by the Moroccan paper industry in order to reduce its carbon footprint. This paper presents an integrated solution to an environmental and energy problem of the companies that generate wet waste biomass. The current new prototype consists of a biogas production system using liquid biomass, a solar installation, and thermodynamic storage derived from a heat pump. Energy balances carried out show that the solar system can reach a thermal efficiency of 70%; the thermal losses of the system are around 53% for the biogas system and 22.6% for the storage and piping system. Further, the results found indicate the average heat demand of the digester reactor is 302 kWh per month, the solar system produced 284 kWh per month (94%) in worth case, which means the solar system is the main source energy and the system solar biogas is a self-energy system. Besides, it was found that the pilot solar biogas system produces about 1100 L of biogas, the analysis of biogas produced prove that it contains 74% of CH4 (814 L) and processes about 3000 L of industrial biomass daily, the biogas conversion efficiency of the whole system is 42%. The economic potential of the current solar biogas system in terms of electricity savings reached 2 MWh per month. The life cycle savings of the current solar system instead of purchasing electricity to meet the energy needs of the biogas process is approximately $4687. Annual emissions of (CO2), carbon monoxide (CO), and nitrogen oxides (NOx) are reduced by 69%, 71%, and 70% respectively. Upscaling the current prototype system to 700 m3 (reactor volume) for the case study of cardboard company industry, shows that the yearly bio-methane (CH4) production is around 52,836 m3 per year, which represent 64% of the total fuel consumption for the current case of cardboard recycling and packaging company.

The anaerobic digestion (AD) has become an alternative source and an attractive treatment method. Up-flow Anaerobic Sludge Blanket (UASB) digester has been designed to treat the Recycled paper mill wastewater (RPMW) in Morocco. This paper provides a research on anaerobic digestion of RPMW using UASB technology. The UASB digester was designed following the characterization of wastewater and the feed rate, with the volume of 70 liters. The UASB reactor treating the RPMW was operated for 130 days with minimal overload problems. The experiments were carried out in the mesophilic temperature (37 °C) at different organic loading rates (OLR). A daily analysis was performed to ensure the efficiency of the digester. In this study, the AD experiment was performed in continuous mode with an effluent inlet flow rate equal to 1 L/h. Using the optimal OLR value 5.18 g COD/Ld and with an effluent 5,7 g COD/L, a biogas yield of 92 N mL/g COD removed (at normal temperature and pressure) was obtained during the RPMW anaerobic treatment. The reactor was operated at an optimal hydraulic retention time (HRT) of 15.14 h with a biogas production volume of the optimal value 62.5 L/d. These results indicate that RPMW can be effectively treated in a UASB reactor with the advantage of producing biogas. We tested our system with RPMW, to see the production capacity of the UASB system, which the objective is to develop the system for the industrial scale., Competing Interests: None., (© 2019 The Authors.)

Objective: The main objective of this study is the evaluation of RPPW anaerobic digestion feasibility at laboratory scale under Mesophilic condition. The experiment is conducted using a two-stage biofilm digester of 5 L capacity with mobile support material., Results: Anaerobic treatment of wastewater from recycled pulp and paper industry in Morocco was tested using a laboratory-scale anaerobic biofilm digester that operated under mesophilic conditions over a 70-day. Chemical oxygen demand (COD) efficiency, volatile and total solid (VS, TS) elimination of the substrate during the process were: 78%, 52% and 48% respectively. The system was stable throughout its operating cycle with an optimum pH (7.24), alkalinity (1750 mg CaCO 3 /L) and a volatile fatty acid value (760 mg/L). The experimental daily biogas production measured reaches a value of 5 L/day with a composition of 71% methane, 27.6% carbon dioxide, 0.2 oxygen and 7713 ppm of the H 2 S. The study results show that the anaerobic biofilm reactor is a suitable technique for recycled pulp and paper wastewater (RPPW) treatment. The reactor shows high performances in terms of process stability, removal efficiency (> 70%) and biogas production., Conclusion: Anaerobic digestion is an efficient waste treatment technology that uses natural anaerobic decomposition to reduce the volume of waste while producing biogas. However, research is needed to strengthen microbial metabolism, biochemistry and the functioning of the rector to improve biogas production. The RPPW AD experiment with biofilm digester technology was stable throughout the operation period. The digester knows an overloaded in the last phase of the experiment which leads to an inhibition of biogas production.