• Journal of Korean Society of Environmental Engineers
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• v.34 no.3
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• pp.214-222
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• 2012

Several acidogenesis batch tests, and BMP (Biochemical Methane Potential) with food waste leachate was tested at various organic loading rates (OLRs) on the mesophilic ($35^{\circ}C$) and thermophilic ($55^{\circ}C$) conditions. In acidogenesis batch test, VS removal efficiencies were 27.3% and 30.6% at $35^{\circ}C$ and $55^{\circ}C$, respectively. Removal efficiency of VS at $55^{\circ}C$ was higher than that at $35^{\circ}C$. With decrease in VS, SCOD increased as reaction time increased. Solubilization efficiency of VS were 27.4% and 33.4% at each reaction temperature within 4 days acid fermentation. Methane yield were 461 and 413 $mLCH_4/gVS$ at mesophilic and thermophilic BMP test, respectively. SCOD solubilizations in the themophilic acid fermenter showed 8~17% higher than those in the mesophilic fermenter. COD removal efficiency showed higher in the mesophilic acid fermenter at low organic loading rate. While at high organic loading rate, it was higher in the thermophilic acid fermenter. VS removal efficiency was higher at the mesophilic temperature, however, it decreased at OLR higher than 6 kg $COD/m^3{\cdot}day$. On the contrary, VS removal efficiency did not decrease but maintain at thermophilic temperature. The amount of methane gas generated from mesophilic methanogenesis digester was 12.6, 21.6, 27.4 L/day at OLR of 4, 5, 6 $COD/m^3{\cdot}day$, respectively. The amount of methane gas generated from themophilic methanogenesis digester was 14.3, 20.6, 25.2 L/day at each OLR, respectively, which is about 15~20 L/day lower than those generated at mesophilic digester.

• Resources Recycling
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• v.24 no.2
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• pp.46-54
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• 2015

In this study, an applicability of thermal pretreatment for primary and secondary sludge, which are generated in a sewage treatment plant, was evaluated. The efficiency and charateristics was investigated with each sludge after pretreatment under the condition of $100{\sim}220^{\circ}C$ for 30 minutes. As the result, it was found that $SCOD_{Cr}$, $NH_4{^+}$, VFAs concentrations increased as the pre-treatment temperature increased. For COD solubilization, it was also highly dependent on an increase of temperature resulting in acceleration on hydrolysis and acid fermentation. In the BMP (Biochemical Methane Potential) experiment, for the primary sludge, it showed the higher biogas production rate at a temperature of $220^{\circ}C$, however, the effect was insignificant (5.6%). Whereas, for the secondary sludge, the increase on biogass production rate was 38.8% ($180^{\circ}C$) and this means that the secondary sludge is more suitable for an applicability of thermal pretreatment.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.6
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• pp.904-909
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• 2012

Acid sulfate soil (ASS) and potential acid sulfate soil (PASS) are distribution in worldwide and originate from sedimentary process, volcanic activity, or metamorphism and are problematic in agriculture and environmental due to their present and potential acidity developed by the oxidation. The PASS was defined as soil materials that had sulfidic layer more than 20 cm thick within 4 m of the soil profile and contained more than 0.15% of total-sulfur (T-S). A tentative interpretative soil classification system was proposed weak potential acid sulfate (T-S, 0.15-0.5%), moderate potential acid sulfate (T-S, 0.5-0.75%) and strong potential acid sulfate (T-S, more than 0.75%). PASS due to excess of pyrite over soil neutralizing capacity are formed. It provides no information on the kinetic rates of acid generation or neutralization; therefore, the test procedures used in acid base account (ABA) are referred to as static procedures. The net acid generation (NAG) test is a direct method to measure the ability of the sample to produce acid through sulfide oxidation and also provides and indication. The NAG test can evaluated easily whether the soils is PASS. The samples are mixed sandy loam and the PAS from the hydrothermal altered andesite (1:3, 1:8, 1:16, 1:20, 1:40, 1:80 and 1:200 ratios) in this study. We could find out that the NAG pH of the soil containing 0.75% of T-S was 2.5, and that of the soil has 0.15% of T-S was 3.8. NAG pH test can be proposed as soil classification criteria for the potential acid sulfate soils. The strong type has NAG pH of 2.5, the moderate one has NAG pH of 3.0, and the weak one has NAG pH of 3.5.

• Journal of the Korea Organic Resources Recycling Association
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• v.25 no.1
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• pp.15-21
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• 2017

In the present work, the synergistic effect of seaweed addition on organic acid production from sludge was investigated. The batch experiment was conducted at various mixing ratios of sewage sludge and seaweed (100:0, 75:25, 50:50, 25:75, 0:100 on a COD basis) under the substrate concentration of 20 g COD/L. The fermentation temperature was conducted under mesophilic condition ($35^{\circ}C$) and a heat-treated ($90^{\circ}C$ for 20 min) anaerobic digester sludge was used as a seeding source to suppress the methanogenic activity, The results showed that the amount of organic acid production increased as the content of seaweed increased: organic acids were 1.45, 3.22, 4.28, 5.24 and 4.82 g COD/L for the mixing ratio of 100:0, 75:25, 50:50, 25:75 and 0:100 respectively. The synergistic effect was calculated based on the organic acid production of individual sludge and seaweed, and was found to be 0.92, 1.14, 1.26 g COD/L at the mixing ratio of 75:25, 50:50 and 25:75, which indicates that 40% of synergy was obtained when 25% of seaweed was added. The synergistic effect could be ascribed to the high C/N ratio and biodegradability of seaweed.