Co-digestion Of Olive Mill Wastewater Research Articles

The Effects of Nanoparticles- Zerovalent Iron on Sustainable Biomethane Production through Co-Digestion of Olive Mill Wastewater and Chicken Manure

The impacts of nanoparticles-zerovalent iron (NP-ZVI) on anaerobic co-digestion (AcoD) were assessed. The production of biogas and methane (CH4), as well as the removal efficiency of volatile solids (VS) and contaminants were investigated in the AcoD of chicken manure (CM) and olive mill wastewater (OMWW) with the addition of NP-ZVI at different concentrations (10–50 mg/g VS) and different sizes resulting from various mixing volume ratios (MVR) of NaBH4:FeSO4.7H2O. The results show that NP-ZVI ≤ 30 mg/g VS at MVR-2:1, MVR-4:1, and MVR-6:1 improves the AcoD. In contrast to 40–50 mg/g VS of NP-ZVI, which caused an inhibitory impact in all of the AcoD stages, as well as a decrease in the contaminant’s removal efficiency, the concentration of 10–30 mg NP-ZVI/g VS at MVR-4:1 achieved a maximum improvement of CH4 by 21.09%, 20.32%, and 22.87%, respectively, and improved the biogas by 48.14%, 55.0%, and 80.09%, respectively, vs. the 0 additives. Supplementing AcoD with NP-ZVI at a concentration of 30 mg/g VS at MVR-4:1 resulted in maximum enhancement of the contaminant removal efficiency, with a total oxygen demand (TCOD) of up to 73.99%, turbidity up to 79.07%, color up to 53.41%, total solid (TS) up to 59.57%, and volatile solid (VS) up to 74.42%. It also improved the hydrolysis and acidification percentages by up to 86.67% and 51.3%, respectively.

Increasing the Content of Olive Mill Wastewater in Biogas Reactors for a Sustainable Recovery: Methane Productivity and Life Cycle Analyses of the Process.

Anaerobic codigestion of olive mill wastewater for renewable energy production constitutes a promising process to overcome management and environmental issues due to their conventional disposal. The present study aims at assessing biogas and biomethane production from olive mill wastewater by performing biochemical methane potential tests. Hence, mixtures containing 0% (blank), 20% and 30% olive mill wastewater, in volume, were experimented on under mesophilic conditions. In addition, life cycle assessment and life cycle costing were performed for sustainability analysis. Particularly, life cycle assessment allowed assessing the potential environmental impact resulting from the tested process, while life cycle costing in conjunction with specific economic indicators allowed performing the economic feasibility analysis. The research highlighted reliable outcomes: higher amounts of biogas (80.22 ± 24.49 NL.kgSV−1) and methane (47.68 ± 17.55 NL.kgSV−1) were obtained when implementing a higher amount of olive mill wastewater (30%) (v/v) in the batch reactors. According to life cycle assessment, the biogas ecoprofile was better when using 20% (v/v) olive mill wastewater. Similarly, the economic results demonstrated the profitability of the process, with better performances when using 20% (v/v) olive mill wastewater. These findings confirm the advantages from using farm and food industry by-products for the production of renewable energy as well as organic fertilizers, which could be used in situ to enhance farm sustainability.

Effect of mixture ratio and organic loading rate during anaerobic co-digestion of olive mill wastewater and agro-industrial wastes

Environmental pollution is a serious concern within the Mediterranean area, this situation results mainly from olive mill wastewaters (OMW), the liquid effluents generated during olive oil extraction. Anaerobic digestion of olive mill wastewaters is negatively affected by nitrogen deficiency, low pH, and the presence of phenolic compounds. This study examines the feasibility of OMW co-digestion with rich nitrogen substrates in batch and continuous mode under mesophilic conditions. Four substrates were tested at different ratios (substrate/OMW) in batch mode. Optimal ratio (substrate/OMW) was 80:20 for poultry manure (PM), 20:80 for both cheese whey (CW) and grass, and 50:50 for slaughterhouse wastewater (SWW). Furthermore, the effect of organic loading rate was assessed in continuous mode, using an anaerobic sequencing batch reactor for the mix (SWW/OMW) at 50:50. The reactor was able to degrade 10 g COD/L/day, as the maximal limit for biogas production and process stability. The results proved that co-digestion of SWW with OMW at 50:50 produced the higher biogas volume in batch mode and ensure good process stability, expressed by high alkalinity (2150 eq mg CaCo3/L) and low rate of volatile fatty acids (VFA) (150 eq mg acetic acid/L). Co-digestion of OMW with SWW is an efficient solution, to solve environmental pollution and recover renewable energy from these two organic wastes.

Assessment of biogas and biofertilizer produced from anaerobic co-digestion of olive mill wastewater with municipal wastewater and cow dung

Abstract Morocco as a part of Mediterranean countries is threatened by the tremendous quantities dejected of different organic wastes. Without any treatment or management strategy, these wastes are dumped illegally in large quantities and can affect natural resources, especially soil and water. Recently, it seems that the anaerobic co-digestion method is one of the best processes available to treat organic wastes. The aim of this work is to investigate the reduction of toxicity after anaerobic co-digestion of three different mixture of organic waste based on olive mill wastewater (OMW), domestic wastewater (DW) and cow dung (CD)), in three bioreactors (B1: OMW+DW/B2: OMW+DW+CD/B3: OMW+CD). The efficiency of this process was evaluated through the digestates quality as bio-fertilizers using a phytotoxicity test, and their characterizations by Fourier-transform infrared spectroscopy (FTIR) and Scanning Electronic Microscopy SEM, and also the biogas yield during the anaerobic co-digestion process. The highest biogas volume was obtained from bioreactor B2 (476.69 mL CH4 g-1 VS); the mixture of the three wastes OMW, DW and CD (1/1/1). Phytotoxicity test indicated that anaerobic co-digestion process reduced slightly the phytotoxicity of substrates. The FTIR spectra and SEM images confirmed that the anaerobic co-digestion process successfully carried out by microstructural changes after the process. Principal component analysis (PCA), Spearman correlations and cluster analysis were combined between biogas produced and all physical–chemical and biological parameters, which indicated that these digestates are unstable.

Improving Anaerobic Co-digestion of Sewage Sludge with Thermal Dried Olive Mill Wastewater

Anaerobic co-digestion of olive mill wastewater (OMW) and sewage sludge (SS) is a promising technique in terms of biogas production and quality. An OMW mixture was subjected to pre-treatment (thermal drying), which can reduce the total COD by 72.8% of 10% OMW mixture. OMW mixtures at concentrations of 2, 5, and 10% were tested. OMW addition can improve biogas production if the mixture exceeds 5% (v/v) concentration in the feed. The digestion of SS produced 31 Nm3/Kgvs and with an addition of OMW increased biogas production in the range of 0.337–0.42 Nm3/Kgvs (2–10% v/v in the feed), where the best addition was 10% with 0.42 Nm3/Kgvs of biogas. VS removal was estimated, it was over 55.2% of 10% OMW about 2.2 times of digestion of SS. Also, COD removal efficiency exceeded 72.2% of 10% OMW which is 1.2 times of 100% SS.

An automated medium scale prototype for anaerobic co-digestion of olive mill wastewater

Olive oil production constitutes one of the most important agro-industrial business for Mediterranean countries, where 97% of the international production is focused. Such an activity, mainly carried out through three phase olive oil mill plants, generates huge amounts of solid and liquid by-products further than olive oil. Physico-chemical features of these by-products depend on various factors such as soil and climatic conditions, agricultural practices and processing. As currently carried out, the disposal of these by-products may lead to numerous problems taking into account management, economic and particularly environmental aspects. Indeed, olive mill wastewater is not easily biodegradable due to its high chemical and biochemical oxygen demand, its high content in phenolic compounds, high ratio C/N and low pH, leading consequently to soil and water source pollution. Considering, the above-mentioned statements, olive mill waste disposal constitutes nowadays a challenge for oil industry stakeholders. It becomes necessary to look for alternative solutions in order to overcome environmental problems and ensure the sustainability of oil industry. Anaerobic co-digestion of olive mill wastewater with other agro-industrial matrices could be one of these solutions; since it offers the possibility to produce green energy and break down toxicological compounds contained in these wastewater for a better disposal of the digested matrices as soil conditioner. In this contest, this note reports the functioning principle of an automated medium scale plant for anaerobic co-digestion of olive mill wastewater.

Optimization of anaerobic co-digestion of olive mill wastewater and liquid poultry manure in batch condition and semi-continuous jet-loop reactor

Anaerobic co-digestion of olive mill wastewater (OMW) with liquid poultry manure (LPM) was investigated in a jet-loop reactor (JLR) as a new approach for upgrading the efficiency of bioprocess. Optimum proportion of LPM was evaluated by determining biochemical methane potential. Methane yields were compared by applying one way ANOVA method followed by post hoc Tukey’s test with a 0.05 significance level. Results demonstrated that the addition of LPM at proportion of 10% and 30% (v/v) improved methane yield of OMW digestion but differences between these mixtures and raw OMW are not significant. JLR results confirmed that the proportion 30% LPM gives the optimum condition for excellent stability of digester. Methane production was significantly high until an organic loading rate of 9.5gCOD/Lreactor/day. Overall; this study indicates the technical feasibility and effectiveness of using JLR as one-stage anaerobic system for the co-digestion of OMW and LPM.

Effect of feedstock composition and organic loading rate during the mesophilic co-digestion of olive mill wastewater and swine manure

In the present study, the optimisation of the mesophilic anaerobic co-digestion process of olive mill wastewaters (OMW) together with swine manure (SM) was investigated. Batch and continuous mode experiments were performed in order to define the most efficient mixing ratio and to determine the performance of the reactors under different organic loading rates (OLR). In batch experiment, the most efficient mixing ratio consisted of 40% OMW and 60% SM, since it presented the highest methane production equal to 277 mL CH4/g COD, which corresponded to 79% of the theoretical yield. It was found that the effectiveness of this mixing ratio was not affected in the continuous operation of the reactors. The stepwise increase of the OLR did not affect negatively biomethanation, although the concentration of the inhibitory compounds of the OMW was higher. Under OLR of 4.4 g volatile solids/(L-feed·day) the methane yield of the reactors fed with 40% OMW reached 373 mL CH4/gVS (78% of the theoretical yield). The findings of the present study proved that the co-digestion of OMW together with SM is a sustainable solution, capable to efficiently treat simultaneously these residual residues.

Statistical modelling of the impact of some polyphenols on the efficiency of anaerobic digestion and the co-digestion of the wine distillery wastewater with dairy cattle manure and cheese whey

The objective of this study was to determine the effectiveness of anaerobic digestion in the treatment of polyphenols (PP) present in olive mill wastewater (OMW) and wine distillery wastewater (WDW). Anaerobic Toxicity Assay (ATA) was conducted to assess the impact of the most representative phenolic compounds present in OMW and WDW: catechol, tannins and p-Coumaric acid, on biogas production. The results from this study show that tannins do not present any inhibitory effect on methanogenesis at a concentration level of 1,664 ppm, whereas catechol has an inhibitory effect at 1,664 ppm. In addition, p-Coumaric acid was strongly inhibitory at 50 ppm. The co-digestion of OMW and WDW with other effluents was proposed as a solution for reducing the load of PP in the anaerobic medium. Biochemical methane potential (BMP) tests were carried out for dairy cattle manure and mixtures of five PP. A central composite design was implemented on the BMP tests to model the biogas production response and the degradation kinetics of PP. The co-digestion of WDW with cattle manure and/or whey was also investigated in BMP tests. The results show that the digestion was optimal at a ratio of 16: 64: 20 (WDW: manure: inoculum) with a maximum biogas yield of 172 mL/g of VS and 66% COD removal.

Co-digestion Of Olive Mill Wastewater and Swine Manure Using Up-Flow Anaerobic Sludge Blanket Reactor for Biogas Production

Swine wastewater (SW) and olive mill wastewater (OMW) are two problematic wastes that have become major causes of health and environmental concerns. The main objective of the current work was to evaluate the efficiency of the co-digestion strategy for treatment of SW and OMW mixtures. Mesophilic batch reac-tors fed with mixtures of SW and OMW showed that the two adapted sludges Gadot and Prigat exhibited the best COD removal capacity and biogas production; therefore both were selected to seed up-flow anaerobic sludge blanket (UASB) continuous reactors. During 170 days of operation, both sludges Gadot and Prigat showed high biodegradation potential. The highest COD removal of 85-95% and biogas production of 0.55 L?g-1 COD were obtained at a mixture consisting of 33% OMW and 67% SW. Under these conditions, an organic load of 28,000 mg?L-1 COD was reduced to 1,500-3,500 mg?L-1. These results strongly suggest that co-digestion technology using UASB reactors is a highly reliable and promising technology for wastewater treatment and biogas production.

Optimisation of the mesophilic anaerobic co-digestion of olive mill wastewater with olive mill solid waste in a batch digester

Anaerobic co-digestion of olive mill wastewater (OMW) with other natural substrates containing high level of nitrogen source such as olive mill solid waste (OMSW) is a new approach for upgrading the anaerobic digestion of OMW. This study is the first investigation that has optimised the amount of OMSW that should be used as a co-substrate to compensate the lack in OMW without the need to add chemical nitrogen substances which are not environmentally and economically desirable. The experiments were carried out on laboratory-scale batch digesters operated at a mesophilic temperature (37°C). Each digester was fed with OMW as a main substrate and OMSW as a co-substrate at different amounts of 28, 56, 112 and 150 g TS/L.OMW respectively. The results indicated that the optimal rate of OMSW used as co-substrate was about 56 g TS/L.OMW. Moreover, it was shown that co-digesting OMSW with OMW in an optimal ratio has increased biogas production and COD removal efficiency from 11.17 ± 2.5 to 30.5 ± 2.5 L/L.digester and from 44.5 ± 3 to 83.4 ± 2%, respectively. Furthermore, it has reduced the start-up time of steady biogas production from 65 ± 25 to 28 ± 15 days.

Modelling of the mesophilic anaerobic co-digestion of olive mill wastewater with olive mill solid waste using anaerobic digestion model No. 1 (ADM1)

The anaerobic digestion model No. 1 (ADM1), conceived by the international water association (IWA) task group for mathematical modelling of anaerobic digestion processes is a structured generic model which includes multiples steps describing biochemical and physicochemical processes encountered in the anaerobic degradation of complex organic substrates and a common platform for further model enhancement and validation of dynamic simulations for a variety of anaerobic processes. In this study the ADM1 model was modified and applied to simulate the mesophilic anaerobic co-digestion of olive mill wastewater (OMW) with olive mill solid waste (OMSW). The ADM1 equations were coded and implemented using the simulation software package MATLAB/Simulink. The most sensitive parameters were calibrated and validated using updated experimental data of our previous work. The results indicated that the ADM1 model could simulate with good accuracy: gas flows, methane and carbon-dioxide contents, pH and total volatile fatty acids (TVFA) concentrations of effluents for various feed concentrations digested at different hydraulic retention times (HRTs) and especially at HRTs of 36 and 24 days. Furthermore, effluent alkalinity and ammonium nitrogen were successfully predicted by the model at HRTs of 12 and 24 days for some feed concentrations.

Implementation of IWA anaerobic digestion model No. 1 (ADM1) for simulating the thermophilic anaerobic co-digestion of olive mill wastewater with olive mill solid waste in a semi-continuous tubular digester

Abstract The anaerobic digestion model No. 1 (ADM1) developed by the international water association (IWA) task group for mathematical modelling of anaerobic digestion processes is the most sophisticated model established for full-scale industrial plants design, systems operational analysis and control, assisting technology transfer from research to industry and a common basis for further model development and validation studies. In this work the original ADM1, implemented in the simulation software package MATLAB/Simulink, was adapted and applied to replicate with reasonable degree of accuracy the thermophilic anaerobic co-digestion of olive mill wastewater (OMW) with olive mill solid waste (OMSW) in a semi-continuous tubular digester. The data set from lab-scale experiments described in our previous work was used to calibrate and validate the model. The simulations results indicated that the modified ADM1 was able to predict reasonably well the steady-state results of gas flows, methane and carbon dioxide contents, pH and total volatile fatty acids (TVFA) observed with all influents concentrations (43, 67 and 130 g COD/l) digested at the hydraulic retention times (HRTs) of 24 and 36 days. Also the reactor failure observed at a HRT of 12 days for an influent concentration of 67 g COD/l was predicted and well justified by the modified ADM1.

Potential for methane production from typical Mediterranean agro-industrial by-products

Abstract This work examines the potential for methane production from anaerobic co-digestion of olive mill wastewater and wine-grape residues with slaughterhouse wastewater. Continuous (mesophilic) and batch (mesophilic and thermophilic) experiments were studied, both with the separate types of by-products and with mixtures. Methane yields from olive oil wastewater, winery residues and slaughterhouse wastewater were 108, 147 and 297 L CH 4 kg −1 COD fed respectively. Co-digestion with 50% olive oil wastewater and 50% slaughterhouse wastewater or 50% winery residues gave a methane yield of 184 and 214 L CH 4 kg −1 COD, respectively. Furthermore, the methane yield was 188 L CH 4 kg −1 COD added, co-digesting a mixture of 50% winery residues and slaughterhouse wastewater. Finally, the same mixtures under thermophilic conditions gave methane yields of 282, 301 and 219 L CH 4 kg −1 COD, respectively. These results suggest that methane can be produced very efficiently by co-digesting olive oil wastewater, wine-grape residues and slaughterhouse wastewater.

Optimization of biogas production from olive-oil mill wastewater, by codigesting with diluted poultry-manure

Optimization of biogas production from olive-mill wastewater (OMW) was attempted by codigesting with diluted poultry-manure (DPM) at mesophilic conditions. A series of laboratory experiments were performed in continuously-operating reactors, fed with mixtures of OMW and DPM at various concentrations. It was concluded that codigestion of OMW with DPM is possible without any dilution of OMW or addition of any chemicals. Biogas production was slightly higher when OMW was added to DPM up to a critical concentration (about 40%, expressed as contribution of OMW to the volatile solids of the mixture), after which production is decreased. The results were further verified by scaling up to a continuously-operating pilot-plant reactor digesting DPM, and confirmed that no negative impact was imposed by adding OMW up to the above critical value.

Thermophilic anaerobic co-digestion of olive mill wastewater with olive mill solid wastes in a tubular digester

Abstract This study investigates for the first time the thermophilic (55 °C) anaerobic co-digestion of olive mill wastewater (OMW) with olive mill solid wastes (OMSW) in laboratory scale semi-continuous tubular digesters. Each digester was fed with an influent composed of OMW and OMSW over a range of hydraulic retention times (HRTs) of 12, 24 and 36 days and at organic loading rates (OLRs) between 1.19 and 10.84 g COD/(l day). The TCOD concentration of OMW were 43, 67 and 130 g COD/l and the amount of the dry OMSW co-digested with OMW was 56 g TS/l. The results indicated that the best methane productivity and SCOD removal efficiency of 46 l/((l OMW) day) and 69%, respectively, were achieved at an OLR of 3.62 g COD/(l day) corresponding to an OMW of 130 g COD/l digested at an HRT of 36 days. Furthermore, the best net energy production from digesters operated at thermophilic temperature was 427 kJ/day higher than from those operated at mesophilic temperature for the same conditions of feed concentration and HRT. In contrast, an HRT of 12 days caused a sharp increase of both total volatile fatty acids (TVFA) and chemical oxygen demand (COD) contents in the effluents and a cessation in methane production for the three influents substrate concentrations studied.

Anaerobic co-digestion of olive mill wastewater with olive mill solid waste in a tubular digester at mesophilic temperature

Anaerobic co-digestion is a well established process for treating many types of organic wastes, both solid and liquid. In this study we have investigated, on a laboratory scale, the anaerobic co-digestion of olive mill wastewater (OMW) with olive mill solid waste (OMSW) using semi-continuous, feeding, tubular digesters operated at mesophilic temperatures. Each digester was fed with an influent, composed of OMW and OMSW, at an organic loading rate (OLR) varying between 0.67 and 6.67 g COD/l/d. The hydraulic retention times (HRT) were 12, 24 and 36 days. The TCOD concentrations of OMW used as the main substrate were 24, 56 and 80 g COD/l; the amount of the dry OMSW used as a co-substrate was fixed to approximately 56 g/l of OMW. The results indicated that the best methane production was about 0.95 l/l/day obtained at an OLR = 4.67 g COD/l/d, corresponding to influent TCOD = 56 g COD/l at an HRT = 12 d. In contrast, the maximum TCOD removal efficiency (89%) was achieved at an OLR = 0.67 g COD/l/d, corresponding to influent TCOD = 24 g COD/l at an HRT = 36 d. Moreover, the inhibition of biogas production was observed at the highest OLR studied.