• Journal of the Korea Organic Resources Recycling Association
• /
• v.20 no.1
• /
• pp.61-70
• /
• 2012

Feasibility of co-digestion was investigated by a series of anaerobic batch experiments using sewage sludge, swine waste, and food waste leachate as substrates. The organic solid wastes were collected from M city, where the daily productions of sewage sludge, swine waste, and food waste leachate were 178 ton/d, 150 ton/d, and 8 ton/d, respectively. Both swine waste and food waste leachate showed superior methane yields, methane productivities, and organic pollutant removal efficiencies compared to sewage sludge. Co-digestion of the total amounts of organic solid wastes would enhance methane production by 5.60 times $(530\;m^{3}\;CH_{4}/d\;{\rightarrow}\;2,968\;m^{3}\;CH_{4}/d)$. However, it also increase the amount of digestate by 1.88 times with 3.79 to 4.92 times higher pollutants (chemical oxygen demands total nitrogen, and total phosphorus) loading rates. Co-digestion of organic solid wastes is a valid strategy to enhance the performance of an anaerobic sludge digester and the energy independence of a wastewater treatment plant. Anyhow,the increment of digestate with higher pollutant loading would need a careful counterplan in the operation of the main stream of the treatment plant.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.27 no.3
• /
• pp.27-39
• /
• 2019

In this study, thermal-alkali pre-treatment (THAP) optimal condition and co-digestion efficiency with THAP of the mixture food waste and sewage sludge were evaluated for improving the performances of co-digestion for mixed food waste and sewage sludge. The optimal condition of THAP was evaluated for solubilization COD, CST(Capillary Suction Time), TTF(Time to Filter), and volatile fatty acids (VFAs) with THAP temperature and NaOH concentration. In addition, the co-digestion of mixed food waste and sewage sludge were evaluated using biochemical methane potential (BMP) test. The optimal THAP reaction temperature and NaOH concentration of food waste and sewage sludge were $140^{\circ}C$ and 60 meq/L to solubilization COD over 20%, CST and TTF under 60sec and VFAs concentration over 12,000 mg-COD/L, respectively. The optimal condition of co-digestion of mixed food waste and sewage sludge equal to THAP condition. Therefore, it was determined that the optimal condition of THAP reaction temperature and NaOH concentration for co-digestion of mixed food waste and sewage sludge were $140^{\circ}C$ and 60 meq/L, respectively.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.21 no.4
• /
• pp.62-71
• /
• 2013

This study was carried out to develope a pre-treatment technology for anaerobic digestion. Breaking down large particles into smaller particles enhances the performance of anaerobic digestion by increasing the hydrolysis of particles. A degree of hydrolysis is the most important factor determining the overall efficiency of methane production. Three types of pre-treatment devices (blade-type crusher, ozonization system, cavitation system) were set up and operated to crush solids in pig slurry in order to enhance biodegradability. The effect of pre-treatment on decreasing granular size within pig slurry by three experimental devices were compared. The highest performance of granulization of pig slurry was attained in a combination of blade-type crusher and ozonization system. In batch experiment, there was an improvement of the methane potential by combined pretreatment with crusher and cavitation. In case of pre-treated slurry, biogas and methane production were 325.9 L and 59.7% respectively, while, in untreated slurry, the production were lower; 298.8 L and 55.7%, respectively. These results indicate that higher anaerobic digestion efficiency of pig slurry can be obtained through the pre-treatment.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.25 no.2
• /
• pp.91-100
• /
• 2017

The purpose of this study is to provide a design and operation technical guideline for meeting the appropriate design criteria to bio-gasification facilities treating organic wastes. In accordance with the government's mid-to long-term policies on bio-gasification and energization of organic wastes, the expansion of the waste-to-energy (WTE) facilities is being remarkably promoted. However, because of the limitation of livestock manure containing low-concentration of volatile solids, there has been increased in combined bio-gasification without installing new anaerobic digestion facilities. The characteristics and common problems of each treatment processes were investigated for on-going 13 bio-gasification facilities. The seasonal precision monitoring of chemicophysics analysis on anaerobic digestor samples was conducted to provide guidelines for design and operation according to the progress of bio-gasification treatment. Consequently, major problems were investigated such as large deviation of organic materials depending on seasons, proper dehumidification of biogas and pretreatment of hydrogen sulfide.

• Journal of Korean Society of Environmental Engineers
• /
• v.30 no.10
• /
• pp.1028-1033
• /
• 2008

Sequential quick crushing and alkali hydrolysis(SeCAH), as a pretreatment for foodwaste, incorporating mechanical crushing and alkali hydrolysis was proposed and investigated in this study. Focuses were placed on the improvement of biodegradability of foodwaste and the estimation of potential inhibitors for anaerobic digestion. The solubility of the pretreated foodwaste by SeCAH was increased 2.5 times rather than mechanical crushing. Considering solubility improvement and energy consumption, 2,000 rpm of crushing strength and 5$\sim$10 sec of crushing time are recommended. After SeCAH, the fraction of large organic particles(>2.36 mm) of foodwaste was sharply decreased from 88.0% to 29.0%, otherwise the fraction of small particles(<75 $\mu$m) was greatly increased from 10.5% to 40.7%. Ammouinum, potassium and sulfate were estimated as potential inhibitors for anaerobic digestion and their concentrations in pig slurry were 3331.3 mg/L, 4256.5 mg/L and 1017.5 mg/L, respectively.

• Korean Journal of Environmental Agriculture
• /
• v.42 no.4
• /
• pp.427-434
• /
• 2023

Large amounts of organic wastes generated in agricultural environments such as crop residues and livestock manure adversely affect the environment. Anaerobic digestion can reduce the amount of organic wastes and convert them into energy at the same time. Efforts are being made to further increase the energy conversion efficiency by using co-anaerobic digestion using two or more substrates. Tomatoes, rice straw, cattle manure, and cattle feces (CF) were used as substrates for anaerobic digestion. Each substrate was subjected to anaerobic digestion and the cumulative biochemical methane production potential was measured, and the biodegradability was calculated. Based on the methane production, CF and tomato were further used for co-anaerobic digestion at different mixing ratios. Among the CF:tomato ratios of 1:1, 1:2, and 2:1, 1:2 produced the most methane and the synergy index was greater 1 indicating that the co-digestion of CF and tomato improved the methane production. Overall, the results showed that the methane production from cattle manure can be improved using tomato residues.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.21 no.1
• /
• pp.13-24
• /
• 2013

• Journal of the Korea Organic Resources Recycling Association
• /
• v.25 no.3
• /
• pp.99-111
• /
• 2017

The purpose of this study is to provide a design and operation technical guideline for meeting the appropriate design criteria to bio-gasification facilities treating organic wastes. Based on the results obtained during the field surveys, the overall design and operation guidelines for bio-gasification facilities, monitoring items, cycle and commissioning period were presented. According to the flow of anaerobic digestion process, Various design factors for bio-gasification facilities were proposed in this study. When designing the initial anaerobic digestion capacity, 10 ~ 30% of the treatment capacity was applied considering the discharge characteristics by the incoming organic wastes. At the import storage hopper process, limit concentration of transporting organic wastes was limited to TS 10 % or less, and limit concentration of inhibiting factor was suggested in operation of anaerobic digester. In addition, organic loading rate (OLR) was shown as $1.5{\sim}4.0kgVS_{in}/(m^3{\cdot}day)$ for the combined bio-gasification facilities of animal manure and food wastes. Desulfurization and dehumidification methods of biogas from anaerobic digestor and proper periods of liquifization tank were suggested in design guideline. It is recommended that the operating parameters of the biogasification facilities to be maintained at pH (acid fermentation tank 4.5~6.5, methane fermentation tank 6.0~8.0), temperature variation range within $2^{\circ}C$, management of volatile fatty acid and ammonia concentration less than 3,000 mg/L, respectively.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.30 no.4
• /
• pp.27-40
• /
• 2022

In this study, the anaerobic digestion potential and thermo-chemical pre-treatment were evaluated for efficient anaerobic co-digestion of dewatered sludge(DS) and food waste(FW). As a result, the degradable organic matter concentration and methane yield of FW were evaluated to 2.2 and 1.3 times higher than that of DS, respectively. In order to increase the amount of biogas production, it was determined that it is desirable to increase the mixing ratio of FW. The efficiency of thermo-chemical pre-treatment was evaluated for the reaction temperature, NaOH concentration, reaction time and mixture ratio. As a result of evaluation through pre-treatment efficiency and dehydration capacity, the optimum pre-treatment conditions were evaluated as follows: reaction temperature 140℃, NaOH concentration 60 meq/L, reaction time 60 min, mixture ratio 1:5(DS:FW). The gas production rate and methane yield increased 1.6 and 1.5 times, respectively, compared to before and after applying the optimum pre-treatment. Therefore, it is necessary to increase the mixing ratio of food waste for efficient anaerobic co-digestion of DS and FW. and it is necessary to increase the solubilization efficiency of waste by application of pre-treatment.

• Journal of the Korean GEO-environmental Society
• /
• v.15 no.9
• /
• pp.13-18
• /
• 2014

BMP test was carried out to evaluate the characteristics for co-digestion of night soil and food waste. 6 types of sludge were tested in 30 days which were raw, excess, digested, night soil/septic tank (1:1), food waste (food : dilution water = 1:1), and mixed sludge. Bio gas was produced actively after 2 days, and continued in 2 weeks. Gas generation amount was decreased rapidly after considerable space of time. Especially maximum productivity of gas was shown in 7~8 days. The ultimate methane yields of raw, excess, digested, night soil/septic tank, food waste, and mixed sludge were 64.63, 67.49, 66.45, 72.44, 107.85, and 46.71 mL $CH_4/g$ VS respectively from Modified Gompertz model. The lag growth phase time and maximum specific methane production rate of mixed sludge were 1.88 day and 80.4 mL/day respectively. The methane potential of mixed sludge was higher than individual sludge. So high methane potential was expected by controlling mixing ratio of food waste. Besides stable operation of digestion tank and the solution of oligotrophic problem were possible.