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The recovery of date palm leaflet waste (DPLW), generated by palms through anaerobic digestion (AD) technology, attracts more attention because of its many economic, social, and environmental benefits. In this study, a laboratory-scale experiment using a continuous stirring tank reactor digester (CSTR) operating in mesophilic semi-batch mode was conducted to evaluate experimental methane production, biodegradability, and organic loading rate (OLR). Besides, a theoretical estimate of methane was assessed using a Buswell–Neave equation. Moreover, three modified kinetic models (Logistic, Gompertz, and Richards) were applied to adjust the experimental methane production from the AD of DPLW. This study showed that the experimental methane yield and biodegradability of DPLW were 133 NmL CH4/g VS and 33%, respectively, while the OLR was 2.76 kg VS/m3.d. The kinetic results showed that all three modified models (Gompertz, Richards, and Logistic) were useful for predicting methane production as a function of the added loads. However, the modified Gompertz model was the most suitable for experimental data, even under critical conditions. Indeed, the modified Gompertz model fitted the experimental methane production with an optimal correlation coefficient R2 = 0.998.

Anaerobic co-digestion of sludge from recycled pulp and paper industry (RPPS) with vinasse effluent from alcohol distilleries (VW) was performed under mesophilic conditions (37 °C) at laboratory scale, using one-liter continuous stirred tank reactors (CSTRs). The physicochemical parameters were monitored during the process. The average pH and alkalinity were 7.7 and 1000 mg CaCO3 Kg−1, respectively, indicating that the process is working well without the risk of acidification. The methane yield and biodegradability of this mixture were determined. The methane yield was about 112 (NmL CH4 g−1 VS added) and biodegradability reached 73%. Nevertheless, in monodigestion of RPPS, the methane yield was 94 (NmL CH4 g−1 VS added) and biodegradability 65%. The anaerobic co-digestion of (RPPS) with (VW) at a proportion of (70:30) improved methane production by 16% and biodegradability by 11%. Bioenergy recovery from industrial (RPPS) is promoted by co-digestion with (VW), and the removal efficiency of 73% indicates the performance of the process adopted. A kinetic study was performed using five models Richards, modified Gompertz, Logistic, Cone, and first order. The results show that Richards' was the most appropriate model for adjusting methane production from (RPPS) and (VW) co-digestion.

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. 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 CaCO3/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 H2S. 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. 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.

The aims of this study were to perform the anaerobic digestion of recycled pulp and paper sludge (RPPS) at laboratory scale, using a continuously stirred tank reactor (CSTR) digester, to determine the methane yield of this type of waste, and to control the physico-chemical parameters to maintain its stability during the experiment. Recycled pulp and paper sludge has an important organic matter with a COD/BOD5 ratio of 1.94, which is easily degradable. The result of anaerobic digestion experiment has given a methane yield coefficient of 159 N mL CH4/g VS, while biodegradability was found around 77% (in VS). The results obtained from the kinetic models studied in this work, mainly the modified Gompertz, first-order, Richards, and Logistic kinetic models show that the difference between the predicted and measured methanogenic potentials was higher in the modified Gompertz kinetic model (0.25–12.94%) than in the Logistic model (0.18–2.69%). The Logistic model showed the best fit for the substrates used. The Logistic, the modified Gompertz, Richards models fitted adequately to cumulative methane production (R2 was 0.9744; 0.9597 and 0.9655, respectively). Specifically, the Logistic model predicted the methane production volume like the experimental within loads added of 2.5 g VS/L.

Palm waste is generated in the oasis and poorly valued by burning in random way. This waste can be recovered in many methods according to their physicochemical characterization. The organic values of EFB could allow us to use anaerobic digestion (AD). The elementary compositions are used to estimate the heating value for thermochemical conversion (TC). The study aim is to explore the energetic potential (Ep) of EFB using the AD and TC. The Ep results are 10.87 and 39.1 GWh/y, respectively.

Kinetics modeling is a necessary step to understand the anaerobic digestion (AD) process. This kinetics depends essentially on the nature of the substrate and the operating conditions. There are several studies on kinetic models of AD related to inhibition phenomena, product formation kinetics, hydrolysis phase, biogas production, and biodegradability. AD technologies are known to be quite complex processes. AD can sometimes suffer from instabilities that are mainly due to the significant fluctuations of some parameters. The aim of this chapter is to show the important role of the kinetic study on the performance of AD. The main kinetics models used to characterize the AD process are discussed.

Highlights • UASB was proposed for RPMW anaerobic treatement under mesophilic conditions. • Start-up up of the UASB reactor was completed in the 24 days. • 80,76 % COD and 90 % TS were removed at an OLR of 7,27 g COD/L d. • At optimal OLR of 8.31 g COD/L d was required to produce 62.51 L/d biogas. • For HRT 15.14 h, after reactor start-up 80.63 % of COD was removed. • The average biogas composition was 72.98 % CH4, 19.76 % CO2, 0.9 % O2., 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.

The treatment of food waste (FW) is an important challenge in developed and undeveloped countries due to the rapid disintegration of this waste. Hence biogas technology is used to produce energy and to reduce the volume of waste. This technology has disadvantages in terms of sensitivity to nutritional imbalance and low biodegradability. In this case, several pretreatments have been applied to improve biogas production such as thermal pretreatment (TP). This study investigated the effects of TP on physico-chemical properties and methane yield (MY) improvement. With the effect of temperature and time treatment, soluble COD was increased and reaching 68.54 ± 2,4 mg/L recorded at (100 °C, 30 min), which was 43. 41% higher than control. In contrast, TP decreased the percentage of VS compared to the raw FW. Furthermore, anaerobic digestion (AD) of FW pretreated at 100 °C during 30min was tested, the MY was (382.82 mLSTP CH4/ g VS) which 23.68 % higher than untreated food waste. Biodegradability was increased from 83.2 ± 3 % to 91.4 ± 4.1 % showing an increase of 9.8 %. Keywords: Anaerobic digestion, Food waste, Methane, Thermal pretreatment, Biogas

The aim of this research was to design a solar heated system to enhance the anaerobic digestion treatment at mesophilic condition for the UASB (Up flow Anaerobic Sludge Blanket) digester system, the solar energy absorbed by flat plate collectors was transferred to heat storage tanks, which continuously supplied an anaerobic reactor with water at a maximum temperature of 37°C. For this purpose, we have developed two models for a 70 l bio-digester coupled to a solar thermal system (low temperature) using the TRNSYS (Transient System Simulation) platform. The thermal performances and the dynamic behavior of the systems under the climatic conditions of the city of Kenitra-Morocco are studied and the two designs were compared between each other in order to optimize the systems which have an excellent thermal performance.

Food chains in general and dairy industries in particular increase from one year to the other; which generates enormous waste, the management of these waste concerned producers. The aim of this study is the energy estimation of the dairy industry sludge. Anaerobic digestion of the dairy sludge (DS) is conducted in a CSTR digester (continuous stirred tank reactor) at mesophilic temperature conditions (37C°) with a retention time of 45 days. The results obtained show that this dairy sludge(DS) has an encouraging proportion of volatile solids around 88 %, the maximum methanogenic yield potential reached 434 (NmL / g VS added) and the biodegradability recorded was 96 % at these conditions. In this context, one tone of dairy sludge could generate approximately 57kwh/year of electric power through the anaerobic digestion process. This will reduce considerably the industries of electrical energy consumption.

Anaerobic digestion (AD) of organic waste requires pretreatment to improve its performance. The substrate chosen for this study is easily degradable it's from a University canteen in Morocco. This process was studied at the laboratory scale, under mesophilic conditions, using a mixed stirred reactor (CSTR: Continuous Stirred-Tank Reactor). The main objective of this research is to study the effect of ultrasonic pre-treatment on methane production. After ultrasonic pretreatment, the waste showed a decrease in VS from 156.2 g/Kg (93.75%) to 134.03 g/Kg (92.95%) and the recorded methanogenic potential was in the order of 461 (NmL CH4/g VS added), which is a 31% improvement compared to the methanogenic potential recorded by an experiment without ultrasonic pretreatment. Thus the process operated under good pH and alkalinity conditions.

Methane yield is one of the important factors that indicate the anaerobic digestion (AD) process efficiency. The AD is an available treatment of recycled pulp and paper sludge (RPPS) and recycled pulp and paper wastewater (RPPW). This process protects the environment and produces methane, which is considered as renewable energy. In this study, the anaerobic treatment of the RPPW and RPPS were studied using 1L completely stirred tank reactor (CSTR) at laboratory scale with mesophilic conditions. However, a kinetic study was carried out using four models in order to compare and adjust the experimental results. The experimental results show that the RPPW and RPPS methane productions were between 691 and 945 mL/g based on volatile solid (VS), and the corresponding digestion time was about 26 days for the both experiment. The corresponding digestion time could be understood through the methane production kinetic models by digestion experiments within a short time. Different kinetics models were tested including Richards, Logistic, modified Gompertz and Cone models. The obtained results show the modified Gompertz model as the suitable model since it gives the lowest deviation from experimental results. Therefore, the proposed model could be used to accurately predict behavior of AD processes.

The aim of this research it is to show how the biogas anaerobic digestion from treatment of recycled pulp and paper wastewater industry (RPPW) can be a renewable energy. Furthermore, a kinetic study of hydrolyzed COD and productions of methane from UASB digester treating RPPW for the continuous test is established. This will allow to reduce the organic matter deposited in landfills and CO2 emissions and to find viable solutions to minimize the environmental impact of RPPW. This study analyses the biogas products and energy recovery processes from a thermic and electric point of view from the theoretical equations. Thus, this study evaluated the performance of mesophilic methanogenic up-flow sludge blanket reactors (UASB) operating continuously in single-stage (UASB I). The maximum methane yields were 250.9 mLCH4/gCOD removed for UASB I, corresponding to 82.7% of the maximum theoretical energy 6.336 kJ/gCOD removed, Methanogenic potential were 4 137 928 m3CH4/year and electrical energy potential were 510 703 MWh/year. The kinetic study allowed us a hydrolysis rate kh = 0.04 indicates a correct simulation for the UASB digester treatment system for RPPW with an R = 99.668%.

The Olive oil industry is one of the most important agro-industrial sectors in the Mediterranean countries, in which Morocco is the world's 5th largest olive oil producer. By-products of this agro-industry such as OMWW and olive mill pomace represent a major challenge for the environment. The high concentration of polyphenols in OMWW and the lack of nitrogen make AD of this substrate difficult. AcoD of OMWW with other substrates is an alternative solution to fill this gap. In the present study, AcoD of OMWW with FW from the Ibn Tofail University campus restaurant was investigated, in order to enhance AD of OMWW in terms of methane production and process stability. Different co-substrates were prepared and tested, in which the content of OMWW varied from 20 to 80 %.The MY and biodegradability were optimal at the mixture 20 % OMWW: 80 % FW showing the values of 302.16 ± 3.04 mLSTP CH4.gVS−1 and 86.0 ± 4.1 % respectively. The process stability was investigated through the alkalinity and the volatile fatty acids ratio VFA/ALK, and the results show that all mixtures were stable except the control test mono AD of OMWW. This stability might be due to the simultaneous presence of ammonia ions from the decomposition of proteins contained in FW and bicarbonate ions. The OLR increased when the added loads increased throughout the conducted experiments. The OLR of the mixture 20 % OMWW: 80 % FW was 2.0 ± 0.1 kg VS. m-3.d−1) higher than OLR of control test (1.45 ± 0.05 kg VS.m-3.d−1). Furthermore, two kinetics models were applied (modified Gompertz model and the Logistic model). The results shown that both models had a good conformity, and the modified Gompertz model was the more appropriate showing a higher values of R2 than logistic model. Moreover, the lag time decreased when the OMWW proportion increased.

The objective of this study is to analyze the perception of Comorian citizens facing the situation of solid waste management (SWM). For this, a qualitative and quantitative approach is conducted on a sample of 300 households. The study shows that 61.1% of households freely dispose a waste on sensitive sites, 19.7% bring waste to collection points and 18.6% benefit from door-to-door. Moreover, 63% of households prefer door-to-door as a means of waste disposal compared to 19.5% who prefer voluntary intake and 17.5% prefer free evacuation. Home sorting concerns only 19.3% of households compared with 80.7% whose dispose mixed waste. Households that are aware of the negative impact of waste on health are 87.5%, against 5%, are unconscious and 7.5% remain without opinion. The study also shows that 40% of households are aware of the negative impact of waste on the environment, against 33% of non-conscious and 27% of non-opinion. The majority of households (58%) are unsatisfied of waste collection services schedules. However, 93.3% of households approve actions carried out by NGO and association. A financial contribution for waste management system improvement of 0.54 USD and 1.08 USD per month was approved by 67% of households.

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.