• Resources Recycling
• /
• v.22 no.1
• /
• pp.64-71
• /
• 2013

Mineral carbonation has been proposed as a possible way for $CO_2$ sequestration. The electric arc furnace slags consist of calcium, magnesium and aluminum silicates in various combinations. If they could be used instead of natural mineral silicates for carbonation, considerable energy savings and $CO_2$ emissions reductions could be achieved. Indirect aqueous carbonation of the slags consists of two steps, extraction of calcium and carbonation. Acetic acid leaching of electric arc furnace slags had been already studied to extract Ca in them, but it was reported that the carbonation of the extracted $Ca^{2+}$ in the leached solution would suffer from too slow kinetics, even at high pressure of $CO_2$. In this work, to develop more efficient extraction of the electric arc furnace slags, hydrochloric acid leaching to separate calcium from them was studied, and the results were compared with the acetic acid ones. The phase boundary between $Ca^{2+}$ and $CaCO_3$ in the solution with pH was determined by thermodynamic calculations. Hydrochloric acid was more effective than acetic acid for the extraction of Ca in electric arc furnace slag, and there is a possibility to recycle an unreacted hydrochloric acid in the leached solution by electrolysis or evaporation.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.25 no.1
• /
• pp.57-65
• /
• 2017

In a column experiment with low rank coal, rice straw was additionally supplied to induce methane gas generation by microorganisms in the state of supplying microorganisms and nutrients, and long-term biogas production characteristics were observed. When the weight ratio of the rice straw to coal was 0.04 or less, there was no significant gas generation. At 0.08, the biogas was generated for about 90 days. However, the methane gas generation was only 5% compared with the vial test result at optimum condition. Therefore, in order to produce biogas in the coal deposit in situ, a reactor that operates at COD concentration of 2000 mg/L or more at a ratio of 1:3 or more of rice straw to coal should be installed on the ground or under the ground. Liquid from the column filled with coal and rice straw and a liquid from vial containing rice straw were analyzed by microbial community analysis using pyrosequencing method, and compared the dominant microbial species among the two samples. In terms of the uniformity and diversity of the bacteria, the coal-filled column showed various species distribution, which has shown to be a disadvantageous microbial distribution to methane production.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.8 no.2
• /
• pp.146-153
• /
• 2000

To elucidate succession of bacterial populations, especially nitrifying bacteria during the composting of cattle manure with apple pomace, fluorescent in situ hybridization(FISH) using rRNA targeted oligonucleotide probes were applied. The density of ammonia-oxidizing bacteria was ranged from $3,3{\times}10^6cells/g$ dw to $13,4{\times}10^6cells/g$ dw with the peak value after 26 composting days whereas that of nitrite-oxidizing bacteria varied between $6.0{\times}10^6cells/g$ dw and $17.2{\times}10^6cells/g$ dw with the peak value after 7 composting days. And the tendency that the numbers of nitrite-oxidizing bacteria were higher than those of ammonia-oxidizing bacteria, and the peak-time of their densities were the same as that of data determined by the ratio of ammonia-oxidizing bacteria and nitrite-oxidizing bacteria to eubacteria. The peak of ammonia-oxidizing bacteria followed the peak of nitrite-oxidizing bacteria, at the late phase of composting process could be probably caused by the depletion of volatile ammonia of composting materials. Besides these results indicate that FISH method is a useful tool for detection of slow growing nitrifying bacteria.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.8 no.2
• /
• pp.140-145
• /
• 2000

This study was performed to investigate whether the earthworm cast could be reused as bulking agent in the whole processing of the food wastes using the earthworm. In addition, the growth conditions of microorganism lived upon earthworm lasts was investigated. Because the raw food wastes used in this experiment had low pH, and high moisture and organic matter contents, it was unsuitable to use as direct feeds to earthworm. However, when the food wastes were mixed with some earthworm cast, the mixtures were suitable to the feed condition and the growth environment of the earthworm. Therefore, it shows the possibility that the earthworm cast be reused as bulking agent for food wastes. In the microbiological investigation on earthworm cast, the bacteria showed most high density among the microbial species. And the microbial density showed higher under the mid-temperature than under high-temperature, and higher under the anaerobic than the aerobic condition. The drying methods of earthworm cast for the moisture adjusting, has no effect on microorganism growth whether natural or artificial drying. And the activity of enzyme presented more highly before the drying than after the drying.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.7 no.5
• /
• pp.129-137
• /
• 2007

It is very urgent to research the proper recycling method of marine dredged soil as construction material for environmental conservation. Couple of developed countries have been lots of related researches on recycling of marine dredged soil for marine environmental conservation. This is highly imperative in our country. A small-scaled model test for underground pipe has been conducted on the use of controlled low strength materials with marine dredged soil. The flexible pipe, which is called PVC, was used. Four different testing materials, such as natural sand, insitu-soil, sand-CLSM with marine dredged soil and insitu-soil CLSM with marine dredged soil, were used. The vertical and lateral displacement of pipe with CLSM is one tenth of common granular materials. Also, the use of CSLM showed lower lateral and vertical pressure than that of common granular materials. The main reason is the effect of cement hardening of CLSM. This could increase of the stiffness of pipe with backfill materials. In this study, the data presented show that marine dredged soil and in-situ soil can be successfully used in CLSM and reduce the deformation and earth pressure on flexible pipe.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.10 no.1
• /
• pp.120-127
• /
• 2002

This study was carried out to evaluate the effects of initial concentration on composting of diesel-contaminated soil. Silt loam was used in this study. Target contaminant, diesel oil, was spiked at about 2,000, 4,000, and 10,000mg/kg of dry soil, respectively. Mix ratio of soil to sludge was 1:0.3 as wet weight basis. Temperature was maintained at $20^{\circ}C$ Volatilization loss of TPH was 0.7-3.5% of the initial concentrations. Volatilization loss of TPH was not increased in proportion to the initial concentration. After 30 days of operation, 86% and 94% of the initial concentrations at about 2,000 and 10,000mg TPH/kg were biodegraded. Normal alkanes were degraded more rapidly than TPH. The compounds of C12 to C14 were volatilized greatly among n-alkanes. The first order degradation rate constants of about 2,000, 4,000, and 10,000mg TPH/kg were 0.079, 0.069, and 0.061/day, respectively. Produced-$CO_2$ and degraded-TPH were correlated highly regardless of the initial TPH concentration(r = 0.97-0.99).

• Journal of the Korea Organic Resources Recycling Association
• /
• v.9 no.2
• /
• pp.71-76
• /
• 2001

Recently, sludge disposal becomes one of the most serious environmental problems. Because the landfilling and ocean dumping of sludge materials will be prohibited in the near future, the proper treatment?disposal methods should be investigated. Also, oyster shells, piled at the coast, cause adverse effects in coastal fishery, public water surface, natural landscape, public health and so on. Thus, the purpose of this study is to evaluate the dissolution characteristic of metal compounds during soil application experiment using sewage treatment sludge mixed with oyster shells. The dissolution experiment conducted 100days under artificial rainfall and farming soil, mixed with sewage treatment sludge and oyster shells, was put into the pots(approx. 0.5L). The results from dissolution experiment as follows. 1. K, Na was $5{\sim}20mg/{\ell}$, and Ca was less than $90mg/{\ell}$. 2. Heavy metals such as Cd, Cu, As, Pb, Cr, Hg are dissoluted far less than the soil pollution guideline. The application of sewage sludge mixed with oyster shells increases pH(soil acidity)and buffer capacity(CEC) of farming soil, and heavy metals are thought to be attached to soil as insoluble forms.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.8 no.4
• /
• pp.100-110
• /
• 2000

Studies were conducted to know effects of the bulking agents (saw dusts, mushroom waste, wheat bran coconut meal, rice hulls) adding o moisture control, fermentation methods (aerobic and anaerobic) and periods (1 to 20 days) of food waste fermentation for animal feeds on chemical compositions and in vitro DDM (digestibility of dry matter). Experiment designs were focussed basically to obtain extension service data. The NDF (neutral detergent fiber) composition in the oak and pine saw dust were 93.5% and 95.4% (DM basis) in respectively. Thus, the fermented food waste feeds using saw dust (50%) increased NDF(12%), and decreased in vitro DDM(48%) compared to those of raw materials before aerobic fermentation. The oak saw dust showed higher DDM compared to pine. Mushroom wastes which is a residues of mushroom culture mixed originally willow saw dust (80%) and wheat bran (20%) showed quite higher feed value compared to both saw dusts. It was found that an in vitro DDM and NDF composition in fermented feeds appeared highly dependent or the NDF composition in bulking agents. With an increase wheat bran ratio substitute mushroom waste showed linearly decreased NDF, and increased in vitro DDM in the fermented food waste feeds. The fermented feeds added bottling agents composed higher NDF resulted in higher NDF and lower in vitro DDM with prolonged fermentation time. The feeds from anaerobic fermentation appeared lower NDF and higher in vitro DDM compared to those of aerobic fermentation.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.8 no.4
• /
• pp.93-99
• /
• 2000

Treatment of shaving scrap, a chrome containing solid scrap generated by leather manufacturing process, has been so far depended on mainly incineration, soil landfill and ocean dumping, which give bad impact on environment and cause pollution. Shaving scrap generates from the mechanical work for controlling the final thickness of leather and its main components are collagen protein and pan of chromium compound. For the purpose of reusing this leather waste as resources, researches in connection with collagen fiber recovery, gelable protein recovery and liquid fertilizer is being speedily progressed. In the experiment, shaving scrap went through wet pulverizing treatment by physical and chemical methods. Then, making the leather sheet evenly, it is mixed with natural latex and every kind of binding materials in the container, and the mixtures were passed through experimental hydraulic press machine and applied to Fourdrinier machine respectively. Lastly, a test for fading out physical strength and properties of multiple-purpose of leather-like material was performed on a continuous leather sheet prepared by the experiment. In result, the physical strength and properties of leather-like material showed noticeable differences according to mixing ratio of binding materials, beating methods and the Ends of binding materials selected, and generally tear strength was the weakest property among others. Also, by the pilot scale experiment in sequence, it was possible to manufacture recycled goods made of soft and hard types of leather-like material with various performances.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.27 no.4
• /
• pp.71-81
• /
• 2019

This research was conducted to improve availability of agricultural by-products, national natural resources that could be used as fertilizer source, by estimating the amount of production and collecting main contents of fertilizer substances from previous studies and data, in order to be used as basic data to investigate national resources that could be used as alternatives for imported oil-cakes in the future. Conversion factor was used to estimate annual production of agricultural by-products for main 34 crop types in 2018. For total agricultural by-products, rice straws accounted at 50.3% for the highest proportion, followed by 8.7% of rice husks, showing that by-products from rice harvest accounted at 59.0% for all by-products. Further, there were listed the contents of fertilizer substances (nitrogen, phosphoric acid, potash) in 40 types of by-products from agricultural areas. The average contents of nitrogen, phosphoric acid, and potash in agricultural by-products were 1.43%, 0.59%, and 1.90%, respectively. As a result of estimating the annual nitrogen supply amount from 26 agricultural by-products in 2018, it was found that it could supply 44,911 tons of nitrogen. The investigated by-products contained fertilizer substances such as nitrogen, phosphoric acid, and potash, but the contents were lower compared to castor oil-cake used as main component of organic fertilizer. Therefore, resource management plan needs to be established for efficient use of by-products because time, location, and nutrient content of agricultural by-product production were extremely different. Research on fertilizer and manure using agricultural by-products need to be conducted to develop and distribute alternatives for imported oil-cakes.