Total Solids Removal Research Articles

Assessment of Sludge Reduction and Biogas Potential from Anaerobic Co-digestion Using an Acidogenically Fermented Fishery Byproduct with Various Agricultural Wastes

Fishery byproducts were acidogenically fermented with agricultural wastes (corncob, cabbage waste, and fruit peel), and fishery acidogenic fermentation broth (FFB) was used to observe sludge reduction and biogas production in anaerobic co-digestion. The experiment was conducted using a batch test for 30 days in mesophilic conditions. Samples with FFB showed a short response delay time of 1.50–3.06 (day), and total solid (TS) and volatile solid (VS) removal efficiencies of 23–43% and 20–30%, respectively, which were higher than those without FFB. In addition, the process produced 2.63–3.86 times more biogas with a methane content of over 70%. These results indicate that FFB improves the biodegradability of sewage sludge and that microbial communities were activated in a short time during the anaerobic co-digestion process. In particular, the highest TS and VS removal efficiency, biogas production, and high methane content were observed in FFB with corncobs. This suggests that nutrients such as sugar and minerals in corncobs may have positively affected the activity of methane-producing archaea. The anaerobic co-digestion process, which combines FFB and sewage sludge, enhanced the treatment efficiency of sludge and has an advantage of energy recovery.

옥수수 대 산발효액을 이용한 혐기성 병합공정에서 C/N비율이 바이오가스 생산과 슬러지 감량에 미치는 영향

The purpose of this study was to find the optimal C/N ratio for sludge reduction and biogas production through a two-step anaerobic co-digestion process of acidogenically fermented maize stalk broth (AFMB) with sewage sludge. AFMB was prepared as follows: Crushed maize stalk were mixed with 20% (v/v) tap water. The mixture was put into a 10-L cylindrical reactor and anaerobically fermented at 100 rpm and 55 ± 2 °C without pH control (initial pH was 7.2 ± 0.3) to improve fermentation efficiency of maize stalks. The ratio of C/N was prepared to 5.32, 8.62, 12.27, 18.15, 24.43 and 30.75 using the mixing of AFMB and sewage sludge for sludge reduction and biogas production in the anaerobic co-digestion process. The highest total solid (TS) and volatile solid (VS) removal efficiency and biogas recovery was observed with C/N ratio of 18.15, which was found to be 58.13%, 67.85% and 1841.05 mL for TS, VS and biogas, respectively. Above C/N ratio of 24, the activation of microorganisms was inhibited by low pH, thereby TS, VS removal efficiency and biogas production were reduced. Therefore, in case of sludge reduction and biogas production in the anaerobic co-digestion process using AFMB, the optimum C/N ratio was recommended between 18-24. In addition, the production of biogas using AFMB in anaerobic co-digestion was determined a methane content of more than 70%, which opens the possibility of biogas production using AFMB.

Development and cost-benefit analysis of a novel process for biofuel production from microalgae using pre-treated high-strength fresh cheese whey wastewater.

In this study, a novel two-step integrated process is proposed to facilitate the microalgae biofuel production as well as fresh cheese whey wastewater (FCWW) treatment simultaneously. The pre- and post-treatment of high-strength FCWW were performed by means of coagulation and algal cultivation, respectively. The pre-treatment of FCWW for maximum removal of chemical oxygen demand (COD), turbidity (TUR) and total solids (TS) as responses was obtained by statistical optimization of coagulation parameters. The maximum removal of COD, TUR and TS at the optimum level of variables was obtained as 68.09%, 47.80% and 73.63%, respectively. The pre-treated FCWW was further treated by Chlorella pyrenoidosa and observed a significant reduction in the above-mentioned responses (87-94%). The maximum algal biomass yield and lipid productivity were observed as 2.44gL-1 and 77.41mgL-1day-1, respectively. Based on promising results of FCWW treatment and its use as a third-generation biodiesel feedstock, a cost-benefit analysis of the developed process was assessed for microalgal oil production. The total profit earned by the integrated process model was $9.59 millionyear-1. Accordingly, the estimated production cost of algal oil (TAG) from the developed system was estimated to be $79.03 per barrel.

Removal of solids and chemical oxygen demand in poultry litter anaerobic digestion with different inocula

Population growth has contributed to increasing poultry production, entailing a high waste loading, mainly poultry litter. One of the alternatives to treat such residues is anaerobic digestion, in which digester startup and generated-digestate quality are related to the material to be digested and to operation conditions, wherein inoculum use is one of the factors. This study therefore aimed to investigate how digestates, such as inocula, influence poultry litter (PL) anaerobic digestion, as well the reduction of solids and chemical oxygen demand (COD). For this, two inocula (bovine and swine digestates) were tested in the digestion process. The inocula were added at loads of 0.67, 1.00 and 1.67 gVS.L-1day-1. A split-plot design was developed and data underwent analysis of variance with means compared by the Tukey's test at 5% significance. Concerning bovine and swine inocula, it was concluded that both are indicated in the process. However, swine inoculum is better indicated because it had a better removal of total solids (TS), volatile solids (VS) and COD.

Anaerobic biological treatment of frozen seafood wastewater

AbstractThe effect of salinity was studied on the anaerobic treatment of raw, frozen seafood wastewater. A single‐stage of four organic loading rates (OLRs) ranging from 0.58 to 1.45 kg COD/m3.day and two stages of five OLRs in acidogenic reactors ranging from 0.29 to 2.31 kg chemical oxygen demand (COD)/m3.day were fed into laboratory‐scale bioreactors. The wastewater contained a COD of 1,735 mg/L with high salinity, sodium ion (Na+) and nitrogen (N) contents of 8.63 parts per thousand 5,071, and 165 mg/L, respectively. In the single‐stage operation, the COD and total volatile solids (TVS) removal reached maxima of 55 and 63%, respectively, at 0.58 kg COD/m3.day. In the two‐stage operation, the COD and TVS removal were 65 and 70% at the most appropriate OLR of 1.16 kg COD/m3.day. At this OLR, the highest CH4 content and CH4 yield obtained were not satisfactory at 26.62% and 71 L (reported at standard temperature and pressure)/kg COD removed, respectively. For both types of operation, the biogas did not contain sufficient methane (CH4) in all tests at all OLRs. The salts, Na+, and N at the levels in this study did not upset the organic removal efficiency but did adversely affect CH4 production. Two‐stage anaerobic operation could not prevent toxicity due to the characteristics of this wastewater.

Biodegradation of dairy wastes using crude enzymatic extract of Yarrowia lipolytica ATCC 9773

Effluents generated by the food industry have become a serious environmental concern. Bioremediation is a biological process developed as an alternative for the treatment of contaminated areas. In current research, the biodegradation of fat, Biochemical Oxygen Demand (BOD5), Chemical Oxygen Demand (COD) and total solids were evaluated in dairy waste employing enzymatic extract of Yarrowia lipolytica ATCC 9773 as biological agents. All the variables were determined following the specifications of the Standard Methods of the American Water Works Association. Enzymatic extract of Y. lipolytica at different concentrations (8, 12 and 16.0%) was used in a fermentative medium at two pHs (5.0 and 6.5) for 32 h. The highest percentages (%) of fat (82.88), BOD (43.32), COD (44.3) and total solids (13.58) removal were obtained using an inoculum concentration of 16% at pH 5.0 for 32 h of fermentation. These results may have industrial relevance for the reduction of contamination of industrial effluents with high levels of fat and other contaminants.

Effects of different conductive nanomaterials on anaerobic digestion process and microbial community of sludge

The effects of four conductive nanomaterials (nano-carbon powder, nano-Al2O3, nano-ZnO, nano-CuO) on sludge anaerobic digestion (AD) performance and microbial community were investigated through a 36-day fermentation experiment. Results showed that biogas production enhanced by 16.9% and 23.4% with nano-carbon powder and nano-Al2O3 added but decreased by 90.2% and 17.3% with nano-ZnO and nano-CuO. Total solids (TS) removal efficiency was increased by 38.73% and 27.11% with nano-carbon powder and nano-Al2O3 added but decreased by 70.67% and 43.70% with nano-ZnO and nano-CuO. Kinetic analysis indicated four conductive nanomaterials could shorten the lag phase of AD sludge with an average rate of 51.75%. 16S rRNA amplicon sequencing results demonstrated microbes such as Syntrophomonas and Methanosaeta were enriched in nano-carbon powder and nano-Al2O3 reactors. However, microbial community diversity and richness were both inhibited by adding nano-ZnO and nano-CuO. Redundancy analysis (RDA) revealed that genera belong to Firmicutes and Chloroflexi could conduce to methanogenesis process.

Identification of potential waste seeds of wildly growing tree species for the production of biogas.

In this experimental study, seeds of wild tree species namely Acacia nilotica, Prosopis juliflora, Albizia lebbeck, and Leucaena leucocephala were explored as potential feedstocks for anaerobic digestion and compared with cattle manure which is a commonly used feedstock. These seeds occur abundantly as waste biomass in tropical and subtropical parts of Asia, Africa, and the USA. An experimental investigation was carried out in large 300-L anaerobic digesters under semi-continuous feed mode for 90days. The average specific methane production yield observed was 0.208Nm3/kg volatile solids (VS) for A. nilotica, 0.227Nm3/kg VS for P. juliflora, 0.219Nm3/kg VS for A. lebbeck and 0.210Nm3/kg VS for L. leucocephala which was found to be higher than cattle manure's yield of 0.146Nm3/kg VS. Experimental analysis revealed an average methane content of more than 52% for all the seeds and a total volatile solid mass removal efficiency of 41.60% for A. nilotica, 44.19% for P. juliflora, 43.76% for A. lebbeck, and 41.41% for L. leucocephala which was higher than 29.7% for cattle manure. The experimental investigations showed that they have a higher biogas production potential than cattle manure indicating their huge scope and suitability as alternative feedstocks, and their use can also mitigate the ecological risk seeds pose by growing into invasive trees.

Safety evaluation of the food enzyme xylose isomerase from the genetically modified Streptomyces rubiginosus strain DP-Pzn37.

The food enzyme is a d‐xylose aldose‐ketose‐isomerase (EC 5.3.1.5) produced with the genetically modified Streptomyces rubiginosus strain DP‐Pzn37 by Danisco US Inc. Although the production strain contains antibiotic resistance genes, the food enzyme was shown to be free from viable cells of the production organism and its DNA. The food enzyme is intended to be used in an immobilised form for the isomerisation of glucose for the production of high fructose syrups. Residual amounts of total organic solids (TOS) are eliminated by the use of an immobilised food enzyme and further removed by the purification steps applied during the production of high fructose syrups using the immobilised enzyme; consequently, dietary exposure was not calculated. Genotoxicity tests did not raise safety concerns. The systemic toxicity was assessed by a repeated dose 90‐day oral toxicity study in rats. The Panel identified a no observed adverse effect level of 85.2 mg TOS/kg body weight (bw) per day, the highest dose tested. Similarity of the amino acid sequence to those of known allergens was searched and no match was found. The Panel considered that, under the intended conditions of use, the risk of allergic sensitisation and elicitation reactions by dietary exposure cannot be excluded, but the likelihood is considered to be low. Based on the data provided, the immobilisation process and the removal of total organic solids during the production of high fructose syrups, the Panel concluded that this food enzyme does not give rise to safety concerns under the intended conditions of use.

Enhancing hydrogenotrophic activities by zero-valent iron addition as an effective method to improve sulfadiazine removal during anaerobic digestion of swine manure

In this study, the feasibility of Fe0 addition for driving sulfadiazine (SDZ) removal during anaerobic digestion of swine manure (SM) was tested. Compared with the Fe0-free digesters spiked with 200 mg/L SDZ (RSDZ), treatments with 5.0 g/L Fe0 (RSDZ/Fe0) significantly accelerated and optimized the acidification process by enriching Clostridia and Bacteroidia (key members responsible for VFAs/H2 production), providing more readily available substrates for methanogenesis. Furthermore, Fe0 increased the overall abundance of hydrogenotrophic methanogens, specifically toxicant resistant Methanoculleus and Methanosphaera spp. were selectively enriched, helping achieve a 36.9% higher CH4 yield and a 26.4% greater total solids removal efficiency. A positive correlation between the solid content and the SDZ concentration adsorbed in SM was observed. The addition of Fe0 increased the distribution of SDZ in liquid and facilitated its removal through the enhanced biodegradation and physicochemical processes. Overall, the total SDZ removal efficiency was improved by 86.8% with Fe0.

Post-treatment of paint industry effluents by filtration using Andropogon biochar (Andropogon gayanus Kunth cv. Planaltina).

This study evaluates the filtration potential of the biomass obtained from Andropogon grass (Andropogon gayanus Kunth cv. Planaltina) that was converted to biochar by pyrolysis. The biochar is used in filtration systems for the post-treatment of paint industry effluents. The biomass is characterized by elemental analysis (CHSN-O), determination of specific compounds (cellulose/hemicellulose/lignin), FTIR, and SEM. The produced biochar is characterized by SEM, TGA, and surface area analysis. The efficiency of the filters is evaluated by the following parameters: color, turbidity, removal of total solids (suspended and sedimentable), chemical oxygen demand (COD), and metals (Al, Cu, Zn, Co, Cd, and Cr(VI)). Over 99% removal of aluminum, cadmium, and hexavalent chromium is achieved. Moreover, almost 100% of COD and solids are removed, whereas turbidity and color are reduced by over 90%.

Bioprocess Evaluation of Petroleum Wastewater Treatment with Zinc Oxide Nanoparticle for the Production of Methane Gas: Process Assessment and Modelling.

The process evaluation of zinc oxide nanoparticle (ZnO NP) was added to enhance the degradation of petroleum wastewater (PWW) fermentation system with different mixing ratios for enhancing methane production. The results showed that the highest methane yield and total solids (TS) removal ratio reached 485mL/g-VS L PWW added and 81.9% at the ZnO NPg-VS L PWW ratio of 4.5:15, respectively. The proposed model CO2 sequester 545mL CO2/L PWW, production rate 750mL CH4 g-VS L PWW/h, and CH4 yield was 4.85L CH4 g-VS L PWW at 4.5:15 of ZnO NPg-VS L PWW. The kinetic analysis indicated that the modified Gompertz model best fitted the actual evolution of methane yields, as evidenced by the low root mean square prediction error (RMSPE) as well as high correlation difference between (Diff.%) the predicted and actual values. The parameters analyses were highlighted that the PWW digestion with ZnO NP substantially enhanced the hydrolysis rate (khyd), methanogenesis potential (fd), lag phase time h (λ), and methane production rate (Rm) of PWW. The evolution of soluble metabolites, utilization of ZnO NP and carbohydrates were also improved by co-fermentation.

Evaluación de producción de biogás y reducción de carga orgánica de vinazas mediante digestión anaerobia

La vinaza es un residuo derivado de la producción de alcohol carburante, que posee elevada carga orgánica disuelta (46%), bajo pH que oscila entre 3-5 y alta demanda química de oxigeno (DQO) de 200-300 mgDQO/L, dichas características hacen de la vinaza un potencial contaminante. Hoy en día, se han buscado métodos que contribuyan a un adecuado manejo de este residuo, como su aprovechamiento para generar energía. En esta investigación se determinó el efecto de la concentración de vinaza y el tipo de lodo inoculante sobre la tasa global de producción de biogás, actividad metanogénica y reducción de carga orgánica durante el proceso de digestión anaerobia. Se utilizaron lodos como fuente de inóculo, provenientes de una PTAR, de una laguna de vinaza, y de laguna de oxidación y enfriamiento; la producción de biogás se cuantificó con la técnica de desplazamiento de líquido, se determinó la actividad metanogénica específica (AME), se determinó la tasa de remoción de DQO y sólidos totales y se aislaron microorganismos metanogénicos. Se encontró que la concentración de 90% de vinaza con lodos de la laguna de oxidación obtuvo los mejores rendimientos, se cuantificó 674.5 mL de biogás durante 18 días en un volumen de trabajo de 400 mL y se calculó la AME de 0.2 gDQOCH4/gSSV.d. Se demostró que a partir de la digestión anaerobia reduce un 25.2% de la DQO y 22.4% de sólidos; los resultados del análisis microbiológico permitieron evidenciar la presencia de microorganismos metanogénicos en el biorreactor anaerobio.

Optimization of coagulation-flocculation process for the palm oil mill effluent treatment by using rice husk ash

A Coagulation-Flocculation (CF) process was used as a pretreatment for Palm Oil Mill Effluent (POME) prior to the subsequent biological processes. In this study, Rice Husk Ash (RHA) was used to explore its potential as a coagulant, in comparison with aluminium sulphate (alum), Al2(SO4)3, for the removal of Chemical Oxygen Demand (COD) and Total Solid (TS) from POME. Important process parameters including coagulant dosage, initial pH and settling time were optimized using Box–Behnken design in Response Surface Methodology (RSM). All the coagulants and coagulated flocs were characterized by using Fourier Transform Infrared spectroscopy (FTIR). POME treated with RHA yielded COD and TS removals up to 52.38% and 83.88%, respectively, under the following optimum conditions: 6.0 g of RHA, initial pH of 3.6 and settling time of 57.00 min. Meanwhile, alum under optimum conditions (6.5 g alum, initial pH of 6.0 and settling time of 41.69 min) produce slightly higher removals of chemical oxygen demand and total solids at 52.36% and 84.94% respectively. The results have shown that RHA is capable of becoming an alternative to alum and efficiently treated POME at its natural pH at relatively lower levels compared to treatment using alum. The present study shows that RHA can be utilized as a new cost-effective coagulant for palm oil mill effluent treatment.

Semi-continuous anaerobic co-digestion of flotation sludge from broiler chicken slaughter and sweet potato: Nutrients and energy recovery

Energy production based on the proper allocation of environmental liabilities is in line with the concept of sustainability. Flotation sludge (S) is a type of waste derived from the physical treatment of the wastewater generated in significant quantities during chicken slaughter in Brazil. If not treated, this wastewater may contribute to pollution, but further treatment provides clean energy and nutrient recycling. The present study aimed at evaluating the reduction of (S) organic load by means of mono and co-digestion with sweet potatoes (P) while promoting its conversion into energy (methane) and nutrients (digestate). Semi-continuous reactors (60 L capacity) were used with a hydraulic retention time of 25 days. The reactors were fed daily with 2.4 L consisting of 60% digestate recirculation, 40% non-chlorinated water and 4.5% total solids (TS). Using nine reactors and six progressive periods, eleven conditions were evaluated with three replicates each. The percentages of (P) and (S) varied from 0 to 100. The best observed condition in terms of energy recovery and TS removal was 60% of P + 40% of S (p ≤ 0.05), as it presented values of at least an increase of 92% in total biogas volume, an increase of 123% in specific methane production, an increase of 98% in specific methane yield and an increase of 44% in TS removal efficiency compared to mono-digestions. The fertilizer potential of the digestate generated in the different conditions was calculated and evaluated according to the area of (P) production. The results varied from 3.6 to 10.8 ha of (P) using 100 m3 of digestate. A multivariate analysis showed that higher amounts of (P) in substrate composition favor energy recycling while higher concentrations of (S) enhance the production of a digestate with valuable agronomic characteristics.

Enhanced mesophilic anaerobic digestion of waste sludge with the iron nanoparticles addition and kinetic analysis

As the functional material, iron nanoparticles effectively promote anaerobic digestion (AD) process, including the hydrolysis-acidification process and the biogas production. In this study, nano zero-valent iron (nZVI) and Fe3O4 nanoparticles (Fe3O4 NPs) were added to AD reactors respectively. The AD process was evaluated by the reactors performances, including pH, biogas yields and compositions, as well as the removal ratio of total solids (TS), volatile solids (VS) and soluble chemical oxygen demand (sCOD). Three models (first-order kinetic model, transfer function model and Cone model) were used to explore the kinetics of AD biogas production. The results showed that adding appropriate dose of nZVI or Fe3O4 NPs enhanced anaerobic digestibility of sludge. The highest cumulative biogas yield of 140.34 L with 0.5 g L−1 nZVI and 137.13 L with 1 g L−1 Fe3O4 NPs were obtained by the 80 days of mesophilic operation, respectively. Cumulative biogas productions of these two reactors were significantly enhanced up to 15.70% and 13.44%. TS removal rates reached >70% in all AD reactors with iron nanoparticles, and the highest sCOD removal rates of nZVI and Fe3O4 NPs digesters on the 80th day were 88.22% and 77.63%, respectively. The results of the three-day fermentation experiment and the kinetic parameters showed that the nZVI or Fe3O4 NPs enhanced the hydrolysis-acidification process of the AD, which eventually promoted biogas production. The Cone model was satisfied with the experimental results, which could be used to evaluate the kinetics of AD with iron nanoparticles more reasonably.

Cassava Wastewater Treatment in Fixed-Bed Reactors: Organic Matter Removal and Biogas Production

The process of cassava starch extraction is associated with the generation of a large volume of liquid wastes from root washing and starch extraction (5 to 7 L.kg-1root). In this context, the objective of this study was to evaluate the treatment of cassava starch wastewater in a horizontal anaerobic fixed bed reactor to the removal of organic matter and generation of biogas. For this purpose, two fixed bed reactors filled with two different types of support materials were used: bamboo rings and flexible PVC rings. The reactors were constructed in polyvinyl chloride (PVC) with 90 cm length and 15 cm diameter. The working volume of R1 (bamboo as support material) and R2 (PVC as support material) were 6.0 and 8.0 L, respectively. In the operation of the reactors, 13 assays (A1 to A13) were carried out with an increase in the organic loading rate (OLR: 1.7 to 15.0 g COD.L-1.d-1) and a decrease in the hydraulic retention time (HRT: 4.0 to 0.8 days). Biogas production followed a similar pattern in both reactors. The highest biogas productions of 1.5 L.L-1.d-1 (R1) and 1.1 L.L-1.d-1 (R2) were verified in the assay 6 in which were applied highest affluent concentration (15,122 mg.L-1), intermediates organic loading rate (5.6 g.L-1.d-1) and hydraulic retention time (2.7 d). The removal of COD increased with the increase of OLR resulting in COD removal values of up to 99%. Total solids removal efficiencies of 79 and 87% were achieved in R1 and R2, respectively. In both reactors, the contact surface of bamboo (132 m2.m-3) and PVC (191 m2.m-3) supported biomass attachment even in highest OLR (15 g.L-1.d-1) and low HRT (0.8 d). The both support material provided conditions to the reactors withstand the variations and reestablish the equilibrium after possible hydraulic and load shocks, constituting a robust system for the treatment of cassava starch wastewater. In these conditions the COD and solids removal remained satisfactory. After a 450-day reactor running, no changes were observed in the composition and structure of the support material, an indication that bamboo and PVC are possible cheap and efficient alternatives for biomass immobilization.

Safety evaluation of the food enzyme glucose isomerase from Streptomycesmurinus (strain NZYM-GA).

The food enzyme is a glucose isomerase (d‐xylose aldose‐ketose‐isomerase; EC 5.3.1.5) produced with a non‐genetically modified Streptomyces murinus strain NZYM‐GA by Novozymes A/S. The glucose isomerase is intended only to be used in an immobilised form in glucose isomerisation for the production of high fructose syrups. Residual amounts of total organic solids are removed by the purification steps applied during the production of high fructose syrups using the immobilised enzyme; consequently, dietary exposure was not calculated. Genotoxicity tests did not raise a safety concern. Similarity of the amino acid sequence to those of known allergens was searched and no match was found. The Panel considered that, under the intended conditions of use, the risk of allergic sensitisation and elicitation reactions by dietary exposure cannot be excluded, but the likelihood to occur is considered to be low. Based on the data provided, the immobilisation process and the removal of total organic solids during the production of high fructose syrups, the Panel concluded that this food enzyme does not give rise to safety concerns under the intended conditions of use.

Characteristics and Anaerobic Digestion of Fruits Wastes from Ubungo-Urafiki Market in Dar Es Salaam

Fruits are susceptible to mechanical damages during their transfer to the markets if they are not packed well in containers. Hence fruits wastes are generated in large quantities and because of their organic nature they decompose, which leads to environmental problems. The objective of this research was to quantify and characterize the fruits wastes generated from the Ubungo Urafiki Market in Ubungo Municipality and to establish the potential treatment of these wastes by anaerobic digestion. The data were collected in the field to establish the characteristics quantity of wastes generated in order to determine the potential degradation of fruit wastes using anaerobic digestion process. The market receives seven main kinds of fruits including pineapples, mangoes, water melons, avocados, oranges; paw paws and ripe bananas, which generate about 4.85 tons of fruit wastes per day. The leading fruits with higher percentage of wastes were water melons and oranges, which generated about 800 kg/day and 797 kg/day, respectively. The results of batch plants experiments showed that the reactor with fruit waste-cattle manure-wood ash mixtures had a maximum biogas yield of 34.2 liters while the reactor with fruit wastes-mixtures had lowest biogas yields of 0.1 liters. The reactor with fruit waste- wood ash mixtures had high volatile solid and total solid removal efficiencies of 8.0% and 14.3%, respectively. For the maximization of biogas production wood ash was recommended in order to raise the pH value of the fruit wastes. The batch reactor used in this study was limiting pH control and therefore activities of methanogenic bacteria. It is recommended to adopt a semi continuous or continuous reactor in order to limit excessive production of organic acids, which are responsible for inhibition of biogas production.

Production of biogas from organic solid residues, by the use of biodigester in bench scale

The urban solid waste that is deposited in the open dumps generates great contamination during its decomposition stage since it undergoes different changes due to the action of the microorganisms that the produce CO2, CH4 and other residual gases that affect the environment and health human. The present work aims to evaluate the efficiency of biogas production from organic solid wastes generated in the University Restaurant of the Technology Center of the Federal University of Rio de Janeiro through anaerobic digestion in biodigesters at scale bench. During this study an anaerobic digestion test was carried out in a bench scale biodigester for a period of 48 days, prepared with organic solid waste, anaerobic sludge and waste water; being analyzed and controlled different chemical parameters, besides the values of temperature and ph. The test prepared for this project consisted of 6% of total solids consisting of solid wastes, anaerobic sludge and wastewater, resulting in an efficiency of removal of total volatile solids of 55% and the production of approximately 38% CH4, 43% CO2 and 10% H2S.