• Journal of Environmental Science International
• /
• v.15 no.9
• /
• pp.897-905
• /
• 2006

This study has been conducted to investigate biodegradation characteristics and optimum mixing ratio for co-digestion with thermophilic acid-fermented food waste and sewage sludge using batch anaerobic digester. As the basis operating conditions for anaerobic digestion, the reaction temperature was controlled $35{\pm}1^{\circ}C$ and stirrer was set 70rpm. Thermophilic acid-fermented food waste and sewage sludge were mixed at the ratio of 10:0, 7:3, 5:5, 3:7, 0:10 and 5;5(food waste : sewage sludge) as the influent substrates. In results of co-digestion according to mixing ratio of thermophilic fermented food wastes and sewage sludge in batch mesophilic anaerobic digestion reactor, $385mL\;CH_4/g\;VS_{added}$ of methane production rate at 1:1 mixing ratio was more than that of any other mixing ratios. Compared with $293mL\;CH_4/g\;VS_{added}$ of methane production rate at 1:1 mixing ratio of food wastes and sewage sludge, pretreatment of food wastes by thermophilic acid fermentation was more effective in co-digestion with sewage sludge.

• Journal of environmental and Sanitary engineering
• /
• v.16 no.1
• /
• pp.108-116
• /
• 2001

It is difficult to task to achieve high biological nutrient removal from municipal wastewater because of low organic content. Volatile fatty acids(VFAs) produced from acid fermentation of food wastes can be utilized as external carbon sources for the biological nutrient process. Significant reduction and stabilization of the food wastes can also be obtained from the acid fermentation. The objective of this study is to evaluate characteristics of acid fermentation of the food wastes. Results obtained from the batch experiment of various organic wastes showed that the food wastes had high potential to be used as an external carbon source because of the largest production of the VFAs with low nitrogen and phosphorus content. The fish waste was found to be the next possible organic waste, while the others such as radish cabbage and molasses waste showed high VFAs consumption potential as a results of high nitrogen and phosphorus content. alkaline hydrolysis of the food waste was carried out using NaOH prior to the acid fermentation. As the alkali addition increased, solubilization of the organics as well as TSS reduction increased. However, fraction of soluble COD to total COD became stable after a sharp increase. Alkali addition greater than 0.5g NaOH per g TS resulted in significant increase in pH.

• KSBB Journal
• /
• v.27 no.1
• /
• pp.51-56
• /
• 2012

This research was to investigate the polyester preparation using waste ethylene glycol (EG) generated from the wastepaper pretreatment process. Waste EG was obtained from using EG five times repeatedly in the pretreatment of wastepaper. The hydroxyl value of the waste EG was 441 mg KOH/g and its composition was 0.68% cellulose, 6.5% hemicellulose, 6.1% lignin, and 86.7% EG. Maleic acid was used as carboxylic acid. The effect of reaction temperature and time except carboxyl group/hydroxyl group ratio on the crosslinkage of the prepared polyester was marginal. Citric acid, lithium hydroxide and dicumyl peroxide were used as additive or catalyst to enhance the crosslinkage of polyester. Among them, 10% of citric acid was found to be most effective. The crosslinkage was 86% when the polyester was prepared at an optimum condition such as $130^{\circ}C$ and 15 minutes, 1.5 of C/H ratio, and 10% of citric acid, and its insoluble percentage in boiling water for 6 hours was 47%. The weight loss of the prepared polyester was approximately 40% when it was buried in damp soil for 5 months, indicating that it is readily biodegradable. This results can provide some information for future development of wastepaper pretreatment by organic solvent.

• Journal of Environmental Science International
• /
• v.23 no.2
• /
• pp.303-312
• /
• 2014

As for chemical characteristics of cultivated media waste, the total content of nitrogen, phosphoric acid, and potassium was 6.93%; organic matter content was 67.78%; pH and EC were 7.20 and 1.46 ds/m, respectively. Organic acids identified during stabilization included citric acid, oxalic acid, fumaric acid, and acetic acid, which was highest. During the stabilization of cultivated media waste, temperature decreased and pH increased on the 15th day, and the germination index was 88 after the period, indicating that at least 15 days of stabilization is needed when cultivated media waste is used for growth material of crop. As for germination characteristics, when the mixture rate of cultivated media waste was 20% and under, germination of cucumber and oriental melon was favorable without difference compared to the control plots. For lettuce and Chinese cabbage, no statistically significant difference was found when the rate was 10% and under compared to the control plots. As for seedling quality after 20 days of sowing, cucumber, oriental melon, and Chinese cabbage showed favorable growth only when the mixture rate of cultivated media waste was 10% and under; lettuce showed lower growth characteristics regardless of mixture rate when compared to the control plots. Cultivated media waste may be significantly useful for cucumber and oriental melon, but not for Chinese cabbage and lettuce.

• Resources Recycling
• /
• v.15 no.5 s.73
• /
• pp.52-56
• /
• 2006

Waste aluminum dross was leached with hydrochloric acid to prepare PAC, poly aluminium chloride, used as water treatment chemicals. Metallic aluminum remained in the waste aluminum dross was dissolved into the hydrochloric acid solution. The solution could be used as PAC after adjusting the required alumina concentration and the basicity. Comparing to the conventional method far preparation of PAC using aluminum hydroxide, material cost could be saved in this method. Also, there is an additional merit in view of recycling of the waste aluminum dross by reducing the amount of waste dross to be landfilled.

• Textile Coloration and Finishing
• /
• v.7 no.2
• /
• pp.9-16
• /
• 1995

When alkaline waste water of PET fabric is treated with sulfuric acid, undegradable material, crude TPA sludge is generated, so that treatment has a serious problem. The result of DMT synthesis using crude TPA sludge generated from PET alkaline waste water were as follows: 1. When crude TPA generated from alkaline waste water is reactioned with methanol under catalyst of sulfuric acid, pure DMT can be obtained. 2. In DMT synthesis from crude TPA, addition of copper sulfate can increase yield, and increasing the amount of sulfuric acid can shorten reaction time.

• 한국신재생에너지학회:학술대회논문집
• /
• 2006.06a
• /
• pp.485-488
• /
• 2006

In order to investigate the possibility of waste mushroom logs as biomass resource chemical and physical characteristics of normal woods and waste mushroom logs such as crystallinity value, energy consumption, total sugar yield after hydrolysis chemical compounds and molecular weight distribution after acid hydrolysis, were examined. In the results, crystallinity of waste mushroom logs which were three year passed after the inoculation was decreased drastically from 49% to 33% during the cultivation. Lignin contents as chemical compounds of normal woods and waste mushroom logs were 21.07% and 18.78%, respectively. By the results of measurement of energy consumption, the size reduction of normal woods required a significantly higher energy than that of waste mushroom logs. In the hydrolysis, total sugar yield by enzyme and acid hydrolysis were high in waste mushroom logs(53% 57.5%) than in normal woods(42.9%, 47.17%). According to the molecular weight distribution using GPC, low molecular weight compounds were distributed in waste mushroom logs. Based on these results, waste mushroom logs have enough potential as material for developing alternative energy because of easily conversion to sugar by various hydrolysis methods and requirement of low energy consumption during size reduction.

• Advances in materials Research
• /
• v.11 no.4
• /
• pp.251-277
• /
• 2022

Disposal of industrial waste in cities where municipal authorities permitting higher floor area ratio coupled with increasing living standards, a lot of demolition waste is being generated. Its disposal is a challenge particularly in megacities where no landfills are available. The ever-increasing cost of building construction materials also necessitates consuming demolition wastes in a useful manner to save fresh natural raw materials. In the present work, the crushed waste glass is used in high-strength concrete as a partial replacement of fine aggregate. The control concrete of grade M60 was proportioned following BIS 10262-2009. The crushed waste glass has been used as a partial replacement with varying percentages of 10, 20, 30, and 40% by weight of fine aggregate. Experimental tests were carried on the fresh and hardened state of the concrete. The effect of crushed waste glass on the workability of the concrete has been investigated. Non-destructive tests, acid attack tests, compressive strength, split tensile strength, and X-ray diffraction analysis was carried out for the control concrete and concrete containing crushed waste glass after 7, 28, and 270 days of normal curing. The results show that for the same w/c ratio, the workability of concrete increases with increasing replaced crushed waste glass content. However, the decrease in compressive strength of the concrete after 28 days of normal curing and further after 28 days of acid attacks, up to 30% replacement level of fine aggregate by the crushed waste glass is insignificant.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.7 no.4
• /
• pp.673-680
• /
• 1997

NaOH, $Na_2CO_3, CaO, Ca(OH)_2$ and $CaCO_3$ are widely used counteractives for neoutralizing the waste sulphuric acid produced during the metal surface treatment process and/or the metal refining process. To reduce the tremendous expenses for the neutralization treatment of the waste sulphuric acid, the sludge from calcination plant and the stainless refining dust in POSCO (Pohang Iron ＆ Steel co. Ltd.) was utilized. For the sludge, it will be effective to use calcined and then hydrated sludge in strong acid region (pH<2) and to use the sludge itself in weak acid region (pH>2), The gypsum, the by-product of this treatment, was tested to fit the industrial standard of gypsum, so it is expected that it will solve the lack of gypsum supply. For the stainless refining dust, the phase and the morphology of produced gypsum from waste suiphuric acid neutralization was compared with those from pure sulphuric acid. Because of high reactivity and reaction temperature, $CaSO_4$ non-hydrate was obtained in pure sulphuric acid. But $CaSO_4$ dihydrate was obtained in waste sulphuric acid. It is also judged to be a good material for a counteractive of the waste sulphuric acid.

• Journal of Energy Engineering
• /
• v.24 no.4
• /
• pp.11-17
• /
• 2015

This study performed acid fermentation pre-treatment to improve production efficiency of methane that is produced as a product in case of anaerobic fermentation by using food waste leachate, and attempted to confirm the acid fermentation optimum through the BMP test by using pre-treated food waste leachate to increase the yield of methane. As a result of the BMP experiment by using acid fermented food waste leachate, the highest yield of methane of 0.220 L/g VS was confirmed in the HRT three-day condition, and in the initial BMP test by pH, pH 6 was 19,920 mg/L that the highest VFA and acetic acid/TVFA(76.2%) were shown. At this time, it was confirmed that the yield of methane was mostly within 10 days that was reduced to around one-third compared to the general methane fermentation (within 30 days). As the yield of methane was 0.294 L/g VS, it showed a high efficiency of around 1.3 times compared to the control group.