• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.2
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• pp.353-359
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• 2015

This study introduces a resource recycling system in urban apartment complex using four different technologies. The four technologies, called 4G, include a production technology for reclaimed water (Green water), a biogas production technology from organic waste (Green biogas), a reuse technology of rainwater (Green rainwater), and urban agropark (Green pyramid). Green water is the technology for producing the reclaimed water from wastewater, rainwater and underground water, and the average concentrations of BOD, SS, T-N and coliform of reclaimed water were 7.8mg/L, ND (not detected), 4.9mg/L and ND, respectively. Green biogas is the technology for producing biogas and effluent after treating organic wastes (e.g. food waste and night soil) discharged from households, and the average production rates of hydrogen and methane were $0.33m^3/m^3/d$ and $0.24m^3/m^3/d$, respectively. Green pyramid, agricultural farm operated by biogas and reclaimed water, provides a healthy and recreational space for residents, and plant growth rates using treated water and reclaimed water showed height of 1.32cm and weight of 112.8g. Therefore, 4G technologies can improve the recycling rate and treatment efficiencies of waste and wastewater in an apartment complex.

• Journal of the Korea Organic Resources Recycling Association
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• v.32 no.2
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• pp.37-48
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• 2024

Wastewater treatment plants (WWTPs) are obligated to reduce carbon emissions as a part of public sector greenhouse gas (GHG) emission reduction targets. However, Sewage Statistics(2022) shows that CO₂ emissions per wastewater treatment volumes have decreased by only 3.03 % compared to 2020, which is far from enough to meet the Nationally Determined Contribution (NDC) targets. This study aimed to find operational conditions of biological reactors that minimize total carbon footprint (CFP). Total CFP considers both direct emissions from biological processes and indirect emissions from energy consumption. A study was conducted using a computer simulation program which is called as EQPS for a 4-stage BNR WWTP. The results showed that total CFP was reduced by 10.97% compared to the design condition when the mixed liquor recirculation (MLR) was set to 100 % of the influent flow. The N₂O emission factor (EF) of the target WWTP was calculated to be 0.138-0.199 %, which is significantly lower than the IPCC default value of 1.6 %. This study proposes a method to minimize total CFP in WWTPs by optimizing biological reactor operation and emphasizes the need for further research on N₂O emission reduction.

• Resources Recycling
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• v.14 no.4 s.66
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• pp.47-52
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• 2005

Carbonate species in aqueous solution play an important role in the determination of chemical properties of water in relation with alkalinity, buffer capacity, biological productivity, and so on. These compounds also have reactive characteristics such as interphasal reactions between solid, liquid, and gas phases. In the absence of solid materials, the total amount and relative abundance of each carbonate species are directly influenced by the partial pressure of $CO_2$ gas in the atmosphere, which in turn significantly affects the properties of aquatic system. In the water/wastewater treatment process along with the wastes treatment and recycling process which occurring in aquatic environment, it is essential to figure out its characteristics for their optimization and one of its most influential features upon these processes is determined by carbonate species. To understand the fundamental aspect of the relationship between the partial pressure of $CO_2$ gas and chemical features of water, especially pH, the working partial pressure of pure $CO_2$ gas that produced by contacting the dry ice with water has been estimated based on equilibrium calculation. The equilibrium constants for the dissociation ot carbonic acid were determined using van't Hoff equation and the distribution diagram of carbonate species according to the pH has been constructed to substantiate the results of equilibrium calculation. The estimated working partial pressure of pure $CO_2$ gas was found to be a function of the concentration of carbonates in solution, which suggesting that Prior evaluation of the working partial pressure of gas is essential for a better understanding of aquatic interactions.

• Clean Technology
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• v.6 no.1
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• pp.39-49
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• 2000

Ultra Rapid Coagulation (URC) can dramatically remove pollutants loaded in wastewater by adding weighted coagulation additives (WCA) and recycling sludge into the coagulation basin to increase settling velocity and surface adsorption ability of floc. Also settling chamber together with lamella plates offers the high rate settling velocity, which can economically treat a considerable amount of pollutants like as combined sewage overflow (CSO) during the heavy rainfall and reduce the pollutants load into the receiving water for securing water source. It was estimated optimal configuration of settling chamber by using fluent model and the possibilities of reusing the sludge generated in this system.

• Journal of Korean Society on Water Environment
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• v.22 no.1
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• pp.97-103
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• 2006

Excess sludge treatment and disposal currently represent a rising challenge for domestic or wastewater treatment plants due to economic, environmental and regulation factors. Conventional gravity sedimentation process has been widely used in sludge thickening. The operation method of the process is very simple, but the process requires long detention time for sludge thickening, uses polymers, and shows low sludge thickening efficiency. To solve the problems, we studied on DAF (Dissolved Air Flotation) system. We use bulking sludge of a paper manufacturing plant. The effects of parameters such as SVI (Sludge Volume Index), storage time, initial concentration and wet density of excess sludge were examined. The results showed that the more SVI was low, the more sludge was thickened. As storage time goes by, SVI was increased and thickening performance was deteriorated. In order to improve flotation performance at high concentration, high recycling ratio and pressure did not increase the concentration due to thickening limitation. The addition of 0.8 g/L of loess was increased flotation efficiency of 1.41 times.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.4 no.4
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• pp.113-125
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• 1984

Water supply has been mainly dependent on the construction of the dams in Korea. It is difficult, however, to continue to construct dams for many reasons, such as the decrease of construction sites, the increase of construction costs, the compensation of residents in flooded areas, and the environmental effects. Water demands have increased and are expected to continue increasing due to the concentration of people in the cities, the rise of the living standard, and rapid industrial growth. It is acutely important to find countermeasures such as development of ground water, desalination, and recycling of waste water to cope with increasing water demands. Recycling waste water includes all means of supplying non-potable water for their respective usages with proper water quality which is not the same quality as potable water. The usages of the recycled water include toilet flushing, air conditioning, car washing, yard watering, road cleaning, park sprinkling, and fire fighting, etc. Raw water for recycling is obtained from drainage water from buildings, toilets, and cooling towers, treated waste water, polluted rivers, ground water, reinfall, etc. The water quantity must be considered as well as its quality in selecting raw water for the recycling. The types of recycling may be classified roughly into closed recycle systems and open recycle systems, which can be further subdivided into individual recycle systems, regional recycle systems and large scale recycle system. The treatment methods of wastewater combine biochemical and physiochemical methods. The former includes activated sludge treatment, bio-disc treatment, and contact aeration treatment, and the latter contains sedimentation, sand filtration, activated carbon adsorption, ozone treatment, chlorination, and membrane filter. The recycling patterns in other countries were investigated and the effects of the recycling were divided into direct and indirect effects. The problems of water reuse in recycle patterns were also studied. The problems include technological, sanitary, and operational problems as well as cost and legislative ones. The duties of installation and administrative organization, structural standards for reuse of water, maintenance and financial disposal were also studied.

• Journal of the Korea Organic Resources Recycling Association
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• v.20 no.4
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• pp.61-74
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• 2012

Industrial complexes in Korea have been vigorously established by economic development plan and development policy of industry in 1960s. Recently, Korean government has promoted Eco Industrial Park (EIP) project to recycle by-products and wastes in industrial park In this study, we analyzed the physical and chemical properties for the sludges discharged from A industrial complex. And we investigated the economic feasibility and environmental impact of sludge to energy facilities. The analysis results indicated that the petrochemical industry were 92% in sludge production, the highest treatment amount was landfill, followed by incineration and recycling and then ocean disposal. Wastewater sludge and process sludge samples are collected and analyzed to use as basic data on economic feasibility and environmental impact. Weighted average heating value of sludge samples was 3,891kcal/kg. Based on this data, installation and operation costs, operation returns of operating the drying facility are estimated, compared with cogeneration facility. And this study examines how the payback period of each simulation(total 8 case) with the important parameter changes. As a result, it was found that what needs the shortest payback period is 3years with connection of drying facility and cogeneration facility based on the government's financial subsidy system.

• Membrane Journal
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• v.11 no.4
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• pp.190-203
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• 2001

In this study the discharged wastewater from a paper plant was filtrated by 4 kinds of tubular carbon ceramic ultrafiltration membranes with periodic water-back-flushing. We could investigate effects of watch-back-flushing period, transmembrane pressure (TMP) and flow rate, and find optimal operating conditions. The back-f1ushing time (BT) was fixed at 3 sec, and fi1tration times (FT) werc changed in 15~60 scc, TMP in 1.00~2.50$kg_{f}$/$cm^2$, and the flow rates in 0.27~1.75 L/min. The optimal conditions were discussed in 7he viewpoints of dimensionless permeate flux (J/J$_{0}$), total permeate volume ($V^T$) and resistance of membrane fouling ($R^f$). Optima1 back-flushing period was BT/FT=0.20, suggesting that the frequent back-flushing should decrease membrane fouling. Optimal TMP in the viewpoint of $V^T$ was 1.00~1.55$kg_{f}$/$cm^2$, suggesting that rising TMP should increase membrane fouling and decrease permeate flux. But, rising f1ow rate should decrease membrane fouling and increase permeate flux. Then, average rejection rates of pollutants filtratedby carbon ceramic membranes were 88~98 % for turbidity, 48~72% fort $COD_{cr}$ and 37~76% for TDS.

• Journal of the Korea Organic Resources Recycling Association
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• v.8 no.4
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• pp.129-137
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• 2000

In this study, biological treatment process of MWWT(Municipal wet-waste Treatment) has been developed through a moduling of the containerized closed ATAD(Auto thermal aerobic digestion) system & closed vertical dynamic acerator, which were used for food waste and cattle manure, respectively. Though biological process has several advantages such as low concentrations of heavy metals and salts, proper and stable C/N ratio and constant reaction rate against the process treating two wastes separately, it has a obstacles of salt concentration and much usage of bulking agent such as wood chip. After rapid oxidation in the boxed tower reactor for 5 days, the content of sewage sludge would be reduced 65% on around, might be mixed with the food waste that had been treated in the static closed reactor during 6 days and put in the secondary static reactor for curing. During composting process, the odor contained in the gas generated from the reactor was removed by passing it through a biofilter as well as the leachate was treated in the wastewater treatment facility. Consequently, it seemed to be possible to compost sewage sludge at mild and stable operating condition and at low cost through the biological ATAD process resulting in the production of organic compost satisfying the specifications regulated by itself.

• Journal of the Korea Organic Resources Recycling Association
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• v.31 no.2
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• pp.63-71
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• 2023

Increased nitrogen in the water system has become an important environmental problem around the world, as it causes eutrophication, algae bloom, and red tide, destroys the water system, and undermines water's self-purification. The most common form of nitrogen in the water system is ammonium ion (NH₄⁺), and the largest portion of ammonium ions comes from wastewater. NH₄⁺ is a major contributor to eutrophication, which calls for appropriate treatment and measures for ammonium removal. This study produced biochar by applying Sorghum × drummondii, a type of biomass with a great growth profile, analyzed the adsorption capacity of Sorghum × drummondii biochar produced from the changing carbonization temperature condition of 200 to 400℃ in the ammonium ion range of 10 to 100 ppm, and used the results to evaluate its potential as an adsorbent. Carbonization decomposed the chemical structure of Sorghum × drummondii and increased the content of carbon and fixed carbon in the biochar. The biochar's pH and electrical conductivity showed high adsorption potential for cations due to electrical conductivity as its pH and electrical conductivity increased along with higher carbonization temperature. Based on the results of an adsorption experiment, the biochar showed 54.5% and 17.4% in the maximum and minimum NH₄-N removal efficiency as the concentration of NH₄-N increased, and higher carbonization temperature facilitated the adsorption of pollutants due to the biochar's increased pores and specific surface area and subsequently improved NH₄-N removal efficiency. FT-IR analysis showed that the overall surface functional groups decreased due to high temperature from carbonization.