Ratio Of Food Waste Research Articles

Door-stepping as a strategy for improved food waste recycling behaviour – Evaluation of a full-scale experiment

Comparisons were made between two groups of households in a multi-family residential area in order to investigate how oral information through a door-stepping campaign can influence household food waste recycling behaviour from a quantitative as well as qualitative perspective. Source-separation behaviour was assessed both through weakly weighting of all source-separated food waste and dry recyclables as well as residual waste generated over a period of 104 weeks, as well as repeated waste composition analyses. Introduction of source-separation of food waste for biogas production significantly decreased the generation of residual waste in the whole case-study area. An average generation of 0.72 and 0.71kg, household−1, week−1 of separately collected food waste was found amongst households receiving and not contacted through the door-stepping campaign respectively. The difference between the groups was not statistically significant. Four waste composition analyses show that the average source-separation ratio of food waste was higher and the ratio of incorrectly sorter material lower in the food waste fraction amongst households where oral information had been provided. A decrease over time in the source-separation ratio of food waste amongst households receiving oral information suggests a low durability of the door-stepping campaign. No signs were seen of increased source-separation ratio or decreased ratio of incorrectly sorted material amongst dry recyclables. The study supports previous findings pointing at accessibility as a key factor for increased recycling behaviour. However, results also suggest that such systems must address convenience also in the household interior.

High-solids anaerobic co-digestion of sewage sludge and food waste in comparison with mono digestions: Stability and performance

System stability and performance of high-solids anaerobic co-digestion of dewatered sludge (DS) and food waste (FW) in comparison with mono digestions were investigated. System stability was improved in co-digestion systems with co-substrate acting as a diluting agent to toxic chemicals like ammonia or Na+. For high-solids digestion of DS, the addition of FW not only improved system stability but also greatly enhanced volumetric biogas production. For high-solids digestion of FW, the addition of DS could reduce Na+ concentration and help maintain satisfactory stability during the conversion of FW into biogas. System performances of co-digestion systems were mainly determined by the mixing ratios of DS and FW. Biogas production and volatile solids (VSs) reduction in digestion of the co-mixture of DS and FW increased linearly with higher ratios of FW. A kinetic model, which aimed to forecast the performance of co-digestion and to assist reactor design, was developed from long-term semi-continuous experiments. Maximum VS reduction for DS and FW was estimated to be 44.3% and 90.3%, respectively, and first order constant k was found to be 0.17d−1 and 0.50d−1, respectively. Experimental data of co-digestion were in good conformity to the predictions of the model.

Methane Production Potential of Food Waste and Food Waste Mixture with Swine Manure in Anaerobic Digestion

Purpose: Methane production potential in aerobic digestion was assessed according to feed to inoculum (F/I) ratio for food waste only, and mixing ratio of two materials for food waste and swine manure to give a basic data for the design of anaerobic digestion system. Methods: Anaerbic digestion test was performed using a lab scale batch reactor at <TEX>$35^{\circ}C$</TEX> for six different feed to inoculum (F/I) ratios (0.50, 0.72, 1.14, 1.50, 2.14 and 3.41), three food waste to swine manure ratios (100:0, 60:40 and 40:60) with two different loading concentrations (10g VS/L and 30g VS/L). Results: For food waste only, the highest biogas yield of 1008 mL/gVS was obtained at 0.50 of F/I. For the co-digestion of food waste and swine manure mixture, the highest biogas yield of 1148 mL/gVS was obtained at a mixing ratio of 40:60 with loading concentration of 10g VS/L. Conclusions: F/I ratio for the food waste only, mixing ratio of food waste and swine manure, and co-substrate loading rate affected the biogas production rate. For the low loading rate, there was not so much difference according to the mixing ratio of food waste and swine manure, but for the high loading rate higher biogas yield was acquired for the co-digestion of food waste and swine manure than for the food waste alone (mixing ratio, 100:0).

혐기성소화에서 가축분뇨와 음식물쓰레기의 혼용에 따른 바이오가스 생산 및 소화액의 액비 특성 연구

Objective of this research was to investigate the characteristics of biogas production in anaerobic digestion reactor with different mixing ratio of food waste and swine manure. It was observed that the highest removal efficiency of organic material was 80% at 60 : 40 of mixing ratio (livestock manure : food waste). And also biogas yield was varied due to different mixing ratio of them. The cumulative biogas yield was highest at 60 : 40 of mixing rate (livestock manure : food waste). For use of the liquefied fertilizer as effluent from anaerobic digester, it was the limited ratio for 30% of co-digested food waste based on its salt content.

Effects of mixture ratio on anaerobic co-digestion with fruit and vegetable waste and food waste of China

The biochemical methane potentials for typical fruit and vegetable waste (FVW) and food waste (FW) from a northern China city were investigated, which were 0.30, 0.56 m 3 CH 4/kgVS (volatile solids) with biodegradabilities of 59.3% and 83.6%, respectively. Individual anaerobic digestion testes of FVW and FW were conducted at the organic loading rate (OLR) of 3 kg VS/(m 3·day) using a lab-scale continuous stirred-tank reactor at 35°C. FVW could be digested stably with the biogas production rate of 2.17 m 3/(m 3·day) and methane production yield of 0.42 m 3 CH 4/kg VS. However, anaerobic digestion process for FW was failed due to acids accumulation. The effects of FVW: FW ratio on co-digestion stability and performance were further investigated at the same OLR. At FVW and FW mixing ratios of 2:1 and 1:1, the performance and operation of the digester were maintained stable, with no accumulation of volatile fatty acids (VFA) and ammonia. Changing the feed to a higher FW content in a ratio of FVW to FW 1:2, resulted in an increase in VFAs concentration to 1100–1200 mg/L, and the methanogenesis was slightly inhibited. At the optimum mixture ratio 1:1 for co-digestion of FVW with FW, the methane production yield was 0.49 m 3 CH 4/kg VS, and the volatile solids and soluble chemical oxygen demand (sCOD) removal efficiencies were 74.9% and 96.1%, respectively.

Design and application of a pre-composting test step to determine the effect of high fat food wastes on an industrial scale in-vessel composting system

The high fat content in food wastes was suspected to inhibit an industrial in-vessel composting process from reaching the European Union Animal By-Product Regulation (composting temperature >70 °C for 1 h). The aim of this study was to design a test step to guide the mixing ratio of food waste to green waste to meet the regulation. A 15-compartment composting unit was designed to contain the compost mixes. Sausage and cheese wastes were mixed with green waste at 1:1; 1:2; 1:3 and 1:4 ratios by wet weight volume. Only the sausage waste mix ratio of 1:4 gave an average temperature of 70 °C for at least 1 h after 2 days of composting (fat content – 17%; C: N ratio – 8.6). All the cheese waste mixes did not reach 70 °C after 15 days of composting. This study demonstrated that using a simple pre-composting test step could reduce the chances of process failure during industrial composting. Although both sausage and cheese wastes are high in fat, they performed very differently in the composting process. Two linear equations were fitted to model the impact of these wastes on the maximum composting temperature.

The Performance of Anaerobic Co-digester of Swine Slurry and Food Waste

In order to assess the performance of co-digester using pig slurry and food waste at the farm scale biogas production facility, the anaerobic facility that adopts the one-stage CSTR of 5 <TEX>$m^3\;day^{-1}$</TEX> input scale was designed and installed under the conditions of the OLR of 2.33 kg <TEX>$m^3\;day^{-1}$</TEX> and HRT of 30 days in an pig farmhouse. Several operation parameters were monitored for assessment of the process performance. The anaerobic facility was operated in three stages to compare the performance of the anaerobic co-digester. In the Stage I, that was fed with a mix of pig slurry to food waste ratio of 7:3 in the input volume, where input TS content was 4.7 (<TEX>${\pm}0.8$</TEX>) %, and OLR was 0.837-1.668 kg-VS <TEX>$m^3\;day^{-1}$</TEX>. An average biogas yield observed was 252 <TEX>$Nm^3\;day^{-1}$</TEX> with methane content 67.9%. This facility was capable of producing an electricity of 626 kWh <TEX>$day^{-1}$</TEX> and a heat recovery of 689 Mcal day-1. In Stage II, that was fed with a mixture of pig slurry and food waste at the ratio of 6:4 in the input volume, where input TS content was 6.9 (<TEX>${\pm}1.9$</TEX>) %, and OLR was 1.220-3.524 kg-VS <TEX>$m^3\;day^{-1}$</TEX>. The TS content of digestate was increased to 3.0 (<TEX>${\pm}0.3$</TEX>) %. In Stage III, that was fed with only pig slurry, input TS content was 3.6 (<TEX>${\pm}2.0$</TEX>) %, and OLR was 0.182-2.187 kg-VS <TEX>$m^3\;day^{-1}$</TEX>. In stage III, TS and volatile solid contents in the input pig slurry were highly variable, and input VFAs and alkalinity values that affect the performance of anaerobic digester were also more variable and sensitive to the variation of input organic loading during the digester operation. The biogas produced in the stage III, ranged from 11.3 to 170.0 <TEX>$m^3\;day^{-1}$</TEX>, which was lower than 222.5-330.2 <TEX>$m^3\;day^{-1}$</TEX> produced in the stage II.

Impact of food waste disposers on the generation rate and characteristics of municipal solid waste

Field surveys were carried out to ascertain the reduction in the generation rate of municipal solid waste as a result of the use of food waste disposers (FWDs). The generation rate and characteristics of garbage and of the food waste ground by FWDs in households were investigated, and the effect of FWDs was discussed. In a medium-sized village, the amount of garbage collected per collection decreased from 251.2 kg to 114.7 kg as a result of FWD use. The unit loading of ground food waste was estimated to be 111 g/cap·day. In a small village, the amount of garbage collected weekly decreased from 175 kg to 112 kg. The average unit loading of ground food waste was measured and found to be 126 g/cap·day. The reduction rate of garbage varied from 25% to 39% monthly and the average reduction rate was 31% throughout the surveying period. Dramatic variations in the characteristics of the collected garbage were recognized: the ratio of food waste on a dry basis declined by more than half, the moisture content decreased to half or less, the combustible matter content increased approximately 1.7 times or more, and the lower heating value increased approximately 2.0 times or more compared to the case without FWD use.

Biogas Production from Anaerobic Co-digestion of Food Waste with Dairy Manure in a Two-Phase Digestion System

Co-digestion of food waste and dairy manure in a two-phase digestion system was conducted in laboratory scale. Four influents of R0, R1, R2, and R3 were tested, which were made by mixing food waste with dairy manure at different ratios of 0:1, 1:1, 3:1, and 6:1, respectively. For each influent, three runs of experiments were performed with the same overall hydraulic retention time (HRT) of 13 days but different HRT for acidification (1, 2, and 3 days) and methanogenesis (12, 11, and 10 days) in two-phase digesters. The results showed that the gas production rate (GPR) of co-digestion of food waste with dairy manure was enhanced by 0.8-5.5 times as compared to the digestion with dairy manure alone. Appropriate HRT for acidification was mainly determined by the biodegradability of the substrate digested. Three-, 2-, and 1-day HRT for acidification were found to be optimal for the digestion of R0, R1, and R2/R3, respectively, when overall HRT of 13 days was used. The highest GPR of 3.97 L/L.day was achieved for R3(6:1) in Run 1 (1 + 12 days), therefore, the mixing ratio of 6:1 and HRT of 1 day for acidification were considered to be the optimal ones and thus recommended for co-digestion of food waste and dairy manure. There were close correlations between degradation of organic matters and GPR. The highest VS removal rate was achieved at the same HRT for acidification and mixing ratio of food waste and dairy manure as GPR in the co-digestion. The two-phase digestion system showed good stability, which was mainly attributed to the strong buffering capacity with two-phase system and the high alkalinity from dairy manure when co-digested with food waste.

Potential Methane Production on Anaerobic Co-digestion of Swine Manure and Food Waste

Anaerobic co-digestion of swine manure and food waste for biogas production was performed in serum bottles at various volatile solids(VS) contents and mixing ratios of two substrates(swine manure:food waste=<TEX>$100:0{\sim}0:100$</TEX>). Through kinetic mode of surface methodology, the methane production was fitted to a Gompertz equation. The ultimate methane production potential of swine manure alone was lower than that of food waste regardless of VS contents. However, it was appeared that maximum methane production potentials in 80 : 20 of the mixing rate at VS 3% was enhanced at 144.7%, compared to its only swine manure. The potential increased up to 815.71 ml/g VS fed as VS concentration and food composition increased up to 3.0% and 20%, respectively. The ultimate amount of methane produced had significantly a positive relationship with that of methane yield rate. Overall, it would be strongly recommended that feeding stocks use 20% of mixing ratio of food waste based on VS 3% contents when operating the anaerobic reactor on site at <TEX>$35^{\circ}C$</TEX> if not have treatment of its anaerobic waste water.

Fundamental characteristics of input waste of small MSW incinerators in Korea

Waste incineration in a small incinerator is a simple and convenient way of treating waste discharged from small areas or from large facilities and buildings such as business centers, marketplaces, factories, and military units. Despite their ostensible advantages, however, many small incinerators frequently suffer from serious problems, e.g., unsystematic waste feeding, unstable combustion, deficient air pollution control devices, and consequently, environmental pollution. To obtain a better understanding of the characterization of wastes in small incinerators, we investigated a series of fundamental characteristics, i.e., physical composition, bulk density, proximate and ultimate analysis, potential energy content, and so on. The main waste components in small incinerators were identified as paper and plastic; the proportion of food waste was less than that in large incinerators. Especially, a low ratio of food waste had a strong influence on other waste characteristics, e.g., lower moisture content and bulk density, and higher potential energy. On the other hand, in contrast with that of HCl, there was no distinguishable linear relationship between Cl content in waste and PCDD/DF concentration in combustion gas.

The optimisation of food waste addition as a co-substrate in anaerobic digestion of sewage sludge.

Food waste has been regarded as the main source of various environmental pollution in Korea due to the high volatile solids (VS) and moisture content caused by the features of dietary habits. The feasibility of food waste as a co-substrate in anaerobic digestion of sewage sludge was investigated in mesophilic and thermophilic conditions using batch tests. Cumulative methane production, dissolved organic carbon (DOC) and volatile fatty acids (VFA) were monitored to find the optimal mixing ratios of food waste and sewage sludge for the enhanced performance of co-digestion. It was observed that adequately mixed food waste led to the enhanced methane production both at mesophilic and thermophilic conditions. However, a conventional linear regression conducted for the optimisation of co-substrate mixing ratios was not accurate in describing exact methane production trends of co-digestion because of the different biodegradability of substrates. Therefore, a remodified Gompertz equation showing nonlinear relationship between variables was developed to find exact information with the same experimental data obtained at 2g VS/l generally used in biochemical methane potential (BMP) tests. Based on an influential parameter, methane production rate (MPR), the optimal mixing ratios of food waste were 39.3% and 50.1% in mesophilic and thermophilic conditions, respectively. To confirm the application of the remodified Gompertz equation, secondary batch tests were conducted with the substrate concentrations of 1-4g VS/l. In overall range tested, the confident mixing ratios of food waste was adjusted to 30-40% and 40% in mesophilic and thermophilic conditions, respectively. The most significant factor for enhanced performance was the improved organic carbon content provided by additional food waste.

Characteristics of hydrogen production from food waste and waste activated sludge

This study was conducted for microbial hydrogen production from food waste and sewage sludge. Thirty three batch tests with different VS concentration (from 0.5 to 5.0 %, w/v) and mixing ratio of food waste to sewage sludge (from 0:100 to 100:0) were performed at 35°C. Heat-treated anaerobic sludge was used to seed the serum bottles. In all the tests, cumulative hydrogen production reached the maximum values within 2.5 days. n-Butyrate was produced simultaneously with hydrogen production, of which the amount was proportional to that of n-butyrate. Clostridium sp. are, therefore, considered to be the dominant microorganisms in this study because these microorganisms are responsible for n-butyrate fermentation. The hydrogen production potential of food waste was found over 34.0 mL/g VS at all the VS concentration. The maximum potential of 59.2 mL/g VS was found at 3.0 % of VS concentration. The potential decreased as sewage sludge composition increased due to the methanogens contained in sewage sludge and low carbohydrate concentration; however, the addition of sewage sludge to food waste enhanced hydrogen yield because of sufficient protein. The maximum hydrogen yield of 1.01 mole H2/mole hexoseadded was achieved at the food waste to sewage sludge ratio of 80:20 at the VS concentration of 3.0 %. The specific hydrogen production rate increased up to 22.6 mL H2/g VSS/h as both food waste composition and VS concentration increased.

Single-stage anaerobic codigestion for mixture wastes of simulated Korean food waste and waste activated sludge.

Korean food waste was treated with a single-stage anaerobic codigester (SSAD) using waste activated sludge (WAS) generated from a municipal wastewater treatment plant. The stability and performance of the system was analyzed. The C/N ratio was improved with increasing food waste fraction of feed mixture. The pH, alkalinity, and free ammonia nitrogen concentration were the parameters used to evaluate the digester's stability. The experimentally determined values of the parameters indicated that there were no methane inhibitions in the digester. Digester performance was determined by measuring the total chemical oxygen demand TCOD), volate solids (VS) removal, methane content in biogas, methane production rate (MPR), and specific methane productivity. Methane content in biogas and MPR were significantly dependent on hydraulic retention time (HRT) and ratio of food waste to WAS. The methane content in biogas decreased at shorter HRT or higher organic loading rate (OLR) with increased food waste fraction. Concerning the performance of the codigester, the optimum operating condition of the SSAD was found to be at an HRT of 10 d with a feed mixture ratio of 50% food waste and 50% WAS. A TCOD removal efficiency of 53.6% and a VS removal efficiency of 53.7% were obtained at an OLR of 5.96 kg of TCOD/(m3 d) and 3.14 kg of VS/(m3 d), respectively. A maximum MPR of 1.15 m3 CH4/(m3 d) and an SMP of 0.37 m3 CH4/kg of VSfeed were obtained at an HRT of 10 d with a methane content of 63%.