Vegetable Solid Waste Research Articles

Passive fungal spore release from fruit and vegetable solid waste

Food substrates in municipal solid wastes processing facilities and open dumpsites are a source for the release of fungal spores into air and can cause potential health and climate effects. Experiments were conducted in a laboratory scale flux chamber to measure the fungal growth and spore release from representative exposed cut fruit and vegetable substrates. The aerosolised spores were measured using an optical particle sizer. The results were compared to experiments conducted previously with a test species (Penicillium chrysogenum) on a synthetic media (czapek yeast extract agar). Significantly higher surface spore densities were observed for the fungi on the food substrates as compared to that on the synthetic media. The spore flux was high initially and then decreased on continued exposure to air. The spore emission flux normalised to the surface spore densities indicated that the emission from the food substrates was lower than the emissions from the synthetic media. A mathematical model was applied to the experimental data and the observed flux trends were explained in terms of the model parameters. A simple application of the data and the model to release from a municipal solid waste dumpsite was shown.

Correlation between empirical formulae based stoichiometric and experimental methane potential and calorific energy values for vegetable solid wastes

The correlation between stoichiometric (sMP, sCEV) and experimental biochemical methane potential (eBMP) and calorific energy values (eCEV) of vegetable wastes were evaluated. The elemental composition based empirical formulae were simulated for vegetable wastes and calculated stoichiometric chemical oxygen demand (sCOD), sMP, sCEV and compared with experimental results. Among twelve vegetable wastes chosen, minimum total solids, volatile solids, eCEV, and eBMP were observed in bottle guard (4.2%), beetroot (79.37%), okra(12.9MJ kg−1), onion (0.15 Nm LCH4 g−1VSr), whereas the maximum was recorded in beetroot (16%), radish (95%), tomato (19 MJ kg−1), tomato (0.42 Nm L CH4 g−1VSr), respectively. Similarly, the minima sCOD, sMP and sCEV was recorded as 1.10gCOD g−1VS (okra), 0.40 Nm L CH4 g−1VSr (onion), 15.89MJ kg−1 (Radish), whereas maxima was observed as 1.82 g COD. g−1VS (tomato), 0.62 Nm L CH4 g−1VSr (tomato), 22.29 MJ kg−1 (tomato). The observed lower and higher biogas yield in onion and tomato waste was coincided with the recorded lower carbon to nitrogen (C/N) ratio (16.31), higher amino sulfoxides (sulfonic acid) content and higher C/N ratio, moisture, glucose and fructose content in the former and later respectively. However, the lowest biogas yield in banana plantain waste in spite of highest C/N ratio was attributed to the presence of high cellulose content. Interestingly, the ascending trend in carbon, hydrogen and nitrogen content per gram of dry vegetable waste was correlated well with increased eCEV, sMP, on contrast reverse trend was depicted for oxygen. Among five different reported sCEV model results correlated with present study, the ultimate analysis based Scheurer-Kestner’s model depicted high R2 (0.89) compared to physical and proximate analysis based sCEV models for vegetable waste. Thus, the observed high correlation between sMP and eBMP (0.80), sCEV and eCEV (0.89), sCOD and eCEV (0.87) confirmed as an alternative short-term method that can replace tedious eBMP and eCEV for the design of biogas plants using vegetable organic solid wastes.

Biogas Production from Fruit and Vegetable Solid Waste Co Digested with Sugar Mill Waste Sludge

Biogas (methane) production from batch anaerobic digesters containing varying concentration of sugar industry wastewater sludge as inoculums and organic fruit and vegetable market solid waste as a substrate was experimentally studied in this research. It was observed that biogas production was optimized with batch anaerobic digestion of fruit and vegetable solid waste. It was carried out for 60 days at room temperature with untreated sugar industry wastewater sludge as an inoculums with the varying concentration 10%, 20% and 30% of the working volume (Weight) of substrate. The performance of reactors was evaluated by measuring the daily biogas production at the room temperature and pH was maintained in the range of 6.8 to7.3 respectively. The maximum cumulative methane production is 597.66 ml/gVS. The biogas yields at the end of the 60days total cumulative biogas for R1, R2 and R3 was obtained as 382.48ml/gVS, 552.66ml/gVS and 597.66ml/gVS respectively from the reactors. At the end of the 60 days total cumulative biogas for Rc(control) was obtained as 196.85ml/gVS. It was observed that the methane content of the biogas generated from the reactors was in the range of 47–56% in control reactor and that forR1, R2and R3 were 56-61%, 60-67% and 65-74% respectively.

Pengaruh Laju Pembebanan Organik terhadap Reduksi Padatan pada Proses Anaerobic Co-Digestion Sampah Sayuran dengan Lumpur SBR

Anaerobic digestion is to treat organic waste such as vegetable solid waste (VSW). Anaerobic co-digestion is the mixture of two or more different waste types with the aim to enhance the efficiency of the anaerobic digestion process. In this study, anaerobic digestion of vegetable solid waste (VSW) is compared to the anaerobic co-digestion of VSW and sequencing batch reactor (SBR) sludge. This investigation is focussed on the varying the organic loading rate (OLR) which is the mixing ratio of VSW to SBR sludge; and pH (6, 7 and 8) of the mixture. The mixtures were kept in serum bottles and placed in a shaker for 7 days at 150 rpm. Experiments with OLR 2:1, VSW composition of 1:2:1:1 and pH 6 produced the highest total biogas in anaerobic co-digestion. Thus, for anaerobic co-digestion, the optimum composition of VSW, OLR and pH are 1:2:1:1, 2:1 and 6 respectively. The range of % reduction in total solids (TS), total suspended solids (TSS) and total dissolve solids (TDS) in anaerobic co-digestion is 4-46, 0-43 and 0-64 respectively. In a comparison with single digestion, only 1 in 5 samples of co-digestion exceed that amount of biogas produced by single digestion and this shows that single anaerobic digestion resulted in higher biogas yield. The range of % reduction in TS, TSS and TDS in anaerobic digestion is 13-54, 15-66 and 9-58 respectively. Comparatively, single digestion performs better in solids removal than anaerobic co-digestion and thus, co-digestion method may not be suitable for all types of organic waste.

Single and interactive effects of process variables on microwave-assisted and conventional extractions of antioxidants from vegetable solid wastes

The aim of this work was to study the single and interactive effects of process variables in microwave-assisted and conventional extraction of antioxidant compounds from asparagus, cauliflower, celery, and chicory wastes using water as solvent. The following variables were investigated: water/sample ratio, extraction time in microwave-assisted extraction; water/sample ratio, extraction time, temperature in conventional extraction. Concerning the microwave-assisted extraction, the highest phenolic recoveries and the highest antioxidant activity were obtained at a solid-to-liquid ratio of 1:2 (w/w) and prolonging the time of treatment up to 4min. In the conventional extraction system, the highest yields were generally obtained at a solid-to-liquid ratio of 1:2 (w/w) and with the combination high temperature-low time of treatment. Cauliflower and chicory wastes showed the highest extraction yields when submitted to microwaves and conventional extraction, respectively. Catechin, ascorbic acid, and quercetin 3-O-glucopyranoside were the main phenolic compounds identified in wastes. The application of conventional extraction system gave higher extraction yields than the microwave-assisted one.

Copper biosorption by pine cone shell and thermal decomposition study of the exhausted biosorbent

Pine cone shell (PCS), a vegetable solid waste has been used as effective and efficient biosorbent for the removal of Cu(II) from aqueous solutions. The biosorbent was characterized by elemental analysis, potentiometric titrations, surface area and pore size distribution and FTIR analyses. Batch adsorption experiments were carried out as a function of solution pH, particle size, biosorbent dosage, contact time, and initial metal ion concentration. Then, equilibrium isotherms and kinetic data parameters were evaluated. Equilibrium data agreed well with Langmuir isotherm model. The biosorption capacities of PCS for Cu(II) were determined at 25°C with the Langmuir model as 6.81mg/g. The kinetics data fitted well into the pseudo-second-order model with correlation coefficient greater than 0.99. Also, dynamic biosorption studies were carried out using a packed-bed column and the main column parameters were determined. Pine cone shell was shown to be a promising biosorbent for Cu(II) removal from aqueous solutions. Finally, the pyrolysis characteristics of native PCS and Cu-loaded PCS were investigated by thermogravimetric analysis (TGA) in order to study the possible recycling of PCS after its use as biosorbent of copper.

Vermicomposting of vegetable-market solid waste using Eisenia fetida: Impact of bulking material on earthworm growth and decomposition rate

Vegetable-market solid waste is produced in millions of tones in urban areas and creates a problem of safe disposal. The aim of this study was to convert vegetable solid waste (VW) amended with wheat straw (WS), cow dung (CD), and biogas slurry (BGS) into vermicompost using earthworm Eisenia fetida. VW was mixed in bulky materials (WS, CD, and BGS) in different ratios to produce eight different combinations for laboratory screening of wastes for 15 weeks. The vermicomposting caused a decrease in organic C (12.7–28%) and C:N ratio (42.4–57.8%), while increase in total N (50.6–75.8%), available P (42.5–110.4%), and exchangeable K (36.0–78.4%) contents. Waste mineralization and humification rates were higher in bedding those containing easy digestible bulky agents, i.e., BGS and CD. Worm-processed material obtained from BGS:VW (1:2) vermibed showed the higher total N (31.3 g kg −1), available P (8.7 g kg −1) and exchangeable K (20.7 g kg −1) contents. The nutrient-rich vermicompost with acceptable C:N ratio ranges (≥1:20) indicates its agronomic potentials. Waste mixtures also supported the earthworm growth and reproduction rates in vermibeds. The results indicated that vermicomposting can be an efficient technology to convert negligible vegetable-market solid wastes into nutrient-rich biofertilizer if mixed with bulking materials in appropriate ratios.

Compostagem aeróbia conjugada de lodo de tanque séptico e resíduos sólidos vegetais

O lodo sanitário, principal subproduto do tratamento de esgotos, constitui um dos maiores problemas ambientais urbanos da atualidade. Em meio a este contexto, objetivou-se nesse estudo avaliar o processo da compostagem conjugada de lodo de tanque séptico (LS) e resíduos sólidos vegetais (RV) e determinar a importância da temperatura para o processo de sanitização do substrato tratado. O experimento, inteiramente casualizado com três tratamentos e três repetições, consistiu de nove reatores aeróbios com 100 litros de capacidade. Os resíduos foram utilizados nas seguintes proporções - T1: 100% RV; T2: 5% LS + 95% RV; T3: 10% LS + 90% RV. A compostagem aeróbia conjugada mostrou ser uma alternativa viável para destruição de ovos de helminto e estabilização dos resíduos, sendo fundamentais para tal, a temperatura, o pH e as relações ecológicas presentes nos reatores.

Biomethanization of mixtures of fruits and vegetables solid wastes and sludge from a municipal wastewater treatment plant

The possible management of Fruit and Vegetable Solid Wastes (FVSWs) through their simultaneous digestion with the primary sludge of Municipal Wastewater Treatment plants is investigated. This alternative allows the recovery of energy and a solid product that can be used as an amendment for soils that generated the residue, while is not expensive. Results indicate that the ratio of FVSWs to sludge and the pH control are the main variables determining the methane production and concentration. NaHCO3 was selected to achieve the pH control. The results for a ratio of 50% sludge together with 10 g NaHCO3/kg of residue are among the best obtained, with a methane yield of about 90 L per kg of volatile solids, and a methane concentration of 40% (v/v) of the biogas. A 50% reduction of the total solids; 21% reduction of the volatile solids (in terms of total solids); and a pH value of the sludge, which is 6.9 indicate that the digested sludge can be a good material for soil amendment.

Regression models of ultimate methane yields of fruits and vegetable solid wastes, sorghum and napiergrass on chemical composition

Several fractions of fruits and vegetable solid wastes (FVSW), sorghum and napiergrass were analyzed for total solids (TS), volatile solids (VS), total organic carbon, total kjeldahl nitrogen, total soluble carbohydrate, extractable protein, acid–detergent fiber (ADF), lignin, cellulose and ash contents. Their ultimate methane yields ( B o) were determined using the biochemical methane potential (BMP) assay. A series of simple and multiple regression models relating the B o to the various substrate constituents were generated and evaluated using computer statistical software, Statistical Package for Social Sciences (SPSS). The results of simple regression analyses revealed that, only weak relationship existed between the individual components such as carbohydrate, protein, ADF, lignin and cellulose versus B o. A regression of B o versus combination of two variables as a single independent variable such as carbohydrate/ADF and carbohydrate + protein/ADF also showed that the relationship is not strong. Thus it does not appear possible to relate the B o of FVSW, sorghum and napiergrass with single compositional characteristics. The results of multiple regression analyses showed promise and the relationship appeared to be good. When ADF and lignin/ADF were used as independent variables, the percentage of variation accounted for by the model is low for FVSW ( r 2 = 0.665) and sorghum and napiergrass ( r 2 = 0.746). Addition of nitrogen, ash and total soluble carbohydrate data to the model had a significantly higher effect on prediction of B o of these wastes with the r 2 values ranging from 0.9 to 0.99. More than 90% of variation in B o of FVSW could be accounted for by the models when the variables carbohydrate, lignin, lignin/ADF, nitrogen and ash ( r 2 = 0.904), carbohydrate, ADF, lignin/ADF, nitrogen and ash ( r 2 = 0.90) and carbohydrate/ADF, lignin/ADF, lignin and ash ( r 2 = 0.901) were used. All the models have low standard error values, which indicate the amount of spread is less. Thus, considering only the higher r 2 values, six models are proposed for predicting the B o based on FVSW data and sorghum and napiergrass data. It would be more convenient if B o could be predicted by analyzing the chemical composition of the substrate rather than performing the long-term batch fermentation. To test the validity of the regression models, chemical constituents of FVSW that were not included in the regression analyses were determined and their experimental B o were determined by BMP assay. All the six models were used to predict the B o from the chemical constituents of these FVSW. It was found that most of the predicted values were within 20% of the experimental B o in models 1, 3 and 6. Since models 3 and 6 used the same variables namely, total soluble carbohydrate, ADF, lignin/ADF, nitrogen and ash, B o can be predicted from these five chemical constituents which accounts for more than 90% of the variation in B o ( r 2 > 90).

04/02849 Biochemical methane potential of fruits and vegetable solid waste feedstocks: Gunaseelan, V. N. et al. Biomass and Bioenergy, 2004, 26, (4), 389–399

04/02849 Biochemical methane potential of fruits and vegetable solid waste feedstocks: Gunaseelan, V. N. et al. Biomass and Bioenergy, 2004, 26, (4), 389–399

Biochemical methane potential of fruits and vegetable solid waste feedstocks

The biochemical methane potential of 54 fruits and vegetable wastes samples and eight standard biomass samples were determined in order to compare extents and rates of their conversion to methane. All the samples were obtained fresh, grown in nutrient enriched environment and belonged to mature age group. The ultimate methane yields (B0) and kinetics of fruit wastes ranged from 0.18 to VS added and 0.016 to , respectively, and that of vegetable wastes ranged from 0.19 to VS added and 0.053 to , respectively. Temperature had no effect on the B0 of mango peels; however, the conversion kinetics were higher at 35°C than at 28°C. All the samples of fruits and vegetable wastes tested gave monophasic curves of methane production. Substantial differences were observed in the methane yields and kinetics among the varieties in mango, banana and orange. Different fruit parts within the same variety showed different yields in orange, pomegranate, grape vine and sapota. The methane yields from the mango peels of some of the varieties, orange wastes, pomegranate rotten seeds and lemon pressings were significantly (P<0.05) higher than the cellulose. Methane yields and kinetics of vegetable wastes in different varieties as well as within different plant parts of the same variety differed. Onion peels exhibited yields significantly (P<0.05) similar to cellulose, while majority of the vegetable wastes exhibited yields greater than VS. These results provide a database on extent and rates of conversion of fruits and vegetable solid wastes that significantly contribute to organic fraction of municipal solid wastes (OF-MSW).

Anaerobic digestion of biomass for methane production: A review

Biological conversion of biomass to methane has received increasing attention in recent years. Hand- and mechanically-sorted municipal solid waste and nearly 100 genera of fruit and vegetable solid wastes, leaves, grasses, woods, weeds, marine and freshwater biomass have been explored for their anaerobic digestion potential to methane. In this review, the extensive literature data have been tabulated and ranked under various categories and the influence of several parameters on the methane potential of the feedstocks are presented. Almost all the land- and water-based species examined to date either have good digestion characteristics or can be pre-treated to promote digestion. This review emphasizes the urgent need for evaluating the inumerable unexplored genera of plants as potential sources for methane production.

Two-phase anaerobic digestion of a mixture of fruit and vegetable wastes

Two-phase anaerobic digestion of a mixture of fruit and vegetable solid wastes was studied at laboratory scale, using digesters operated in the mesophilic range. An optimal configuration for a hybrid (up-flow anaerobic sludge bed-anaerobic filter) digester was determined, in order to improve the methanogenic step. Biodegradation achieved in two weeks was around 75%. The process was stable, even when the pH was at the lowest levels (around 5, in the hydrolyzer). The distribution and concentration of volatile fatty acids produced was also studied.

Two-phase methanization of solid vegetable wastes

Single- and two-phase anaerobic digestion of vegetable solid wastes were compared at laboratory scale. Both mesophilic and thermophilic liquefaction and acidogenesis were shown to be maximal when the pH was maintained at approximately 6·5 in the reactor. The distribution and concentrations of the Volatile Fatty Acids and alcohols produced varied with the temperature, the nature of the wastes and the retention time. Methanogenic fermentation of the liquefaction products was efficiently performed in an anaerobic filter and high methane productivities were obtained. Maximal overall methane productivity was attained when the filter productivity was approximately 5 liters of methane per liter per day. Phase separation under mesophilic conditions resulted in significantly higher methane productivity than was obtained by operation in a single-stage CSTR reactor. Under thermophilic conditions, the advantage of two-phase operation was far less marked.

Laboratory scale anaerobic digestion of fruit and vegetable solid waste

Anaerobic digestions that were fed waste apple, corn cobs, apple press cake, extracted sugarbeet pulp, pineapple pressings or asparagus waste were stable in trials lasting up to 226 days. Loading rates of 3·5−4·25 kg m −3 day −1 and conversions of 88–96% of the organic solids fed were obtained by ensuring adequate levels of alkalinity, nitrogen and other nutrients during digestion. Gas yields ranged from 0·429 to 0·568 litre (50–60% methane) per gram organic solids fed. For reasons not understood, gas yields from digestion of apricot waste declined after 63 days from 0·477 to 0·137 litre g −1 of feedstock.