• Journal of the Korea Organic Resources Recycling Association
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• v.29 no.1
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• pp.19-27
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• 2021

Hydroponic farming is a method to grow a plant without soil. Plants can be grown on water or hydroponic growing media, and they are fed with mineral nutrient solutions, which are fertilizers dissolved into water. Hydroponic farming has the advantage of increasing plant productivity over conventional greenhouse farming. Previous studies of hydroponic nutrient wastewater from acyclic hydroponic farms pointed out that hydroponic nutrient wastewater contained residual nutrients, and they were drained to a nearby river bank which causes several environmental issues. Also, previous studies suggest that excessive use of the nutrient solution and disposal of used hydroponic growing media and crop wastes in hydroponic farms are major problems to hydroponic farming. This study was conducted to determine the impact of hydroponic nutrient wastewater, used hydroponic growing media, and crop wastes from acyclic hydroponic farms on the surrounding environment by analyzing water quality and soil analysis of the above three factors. Three soil cultivation farms and several hydroponic farms in the Gangwon C region were selected for this study. Samples of water and soils were collected from both inside and outside of each farm. Also, a sample of soil and leachate from crop waste piles stacked near the farm was collected for analysis. Hydroponic nutrient wastewater from acyclic hydroponic farm contained an average of 402 mg/L of total nitrogen (TN) concentration, and 77.4 mg/L of total phosphate (TP) concentration. The result of TP in hydroponic nutrient wastewater exceeds the living environmental standard of the river in enforcement decree of the framework act on environmental policy by 993.7 times. Also, it exceeds the standard of industrial wastewater discharge standards under the water environment conservation act by 6~19 times in TN, and 2~27 times in TP. Leachate from crop waste piles contained 11,828 times higher COD and 395~2662 times higher TP than the standard set by the living environmental standard of the river in enforcement decree of the framework act on environmental policy and exceeds 778 times higher TN and 5 times higher TP than the standard of industrial wastewater discharge standards under the water environment conservation act. For more precise studies of the impact of hydroponic nutrient wastewater, used hydroponic growing media, and crop wastes from acyclic hydroponic farms on the surrounding environment, additional information regarding a number of hydroponic farms, arable area(ha), hydroponic farming area, seasonal, weather, climate factor around the river, and the property of the area and farm is needed. Analysis of these factors and additional water and soil samples are needed for future studies.

• Korean Journal of Environmental Agriculture
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• v.29 no.2
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• pp.146-151
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• 2010

In order to improve T-N and T-P removal in HF (horizontal flow)-HF hybrid constructed wetlands by natural purification method for treating the hydroponic wastewater in greenhouses, the efficiency of water treatment as affected by the injection method of hydroponic wastewater, the addition of special filter media, the particle size of filter media, and the injection ratio of hydroponic wastewater in $1^{st}$ HF and $2^{nd}$ HF beds were investigated in small-scale HF-HF hydroponic wastewater treatment apparatus. Removal rate of T-P in the water in HF-HF hydroponic wastewater treatment apparatus with calcite as affected by addition method of special filter media was higher than that in HF-HF hydroponic wastewater treatment apparatus with other filter media. Removal rate of BOD, COD, SS, T-N and T-P in the water in mixed filter media with calcite were 86, 84, 87, 50 and 97%, respectively. Removals of pollutants except for T-P in the water were slightly different. Therefore, it should be considered that the removal rate of T-P was good for calcite in HF-HF hydroponic wastewater treatment apparatus. To improve T-N and T-P removal, the optimum particle size of filter media was 1.2 mm, and the optimum injection ratio ($1^{st}$ HF bed : $2^{nd}$ HF bed) of hydroponic wastewater was 60:40.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.5
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• pp.764-771
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• 2012

In order to develop constructed wetlands for treating hydroponic wastewater in greenhouse, actual constructed wetlands were used the obtained optimum condition in previous study, and the removal rate of pollutant in the water according to 4 kinds connection method of piping such as system A (UP-UP stream), system B (UP-DOWN system), system C (DOWN-UP stream) and system D (DOWN-DOWN stream) were investigated. Removal rate of biochemical oxygen demand (BOD), chemical oxygen demand (COD), suspended solids (SS), total nitrogen (T-N) and total phosphorus (T-P) by system A (UP-UP stream) connection method in actual constructed wetlands were slightly higher than other systems. At the system A, the removal rate of BOD, COD, SS, T-N and T-P were 88, 77, 94, 54 and 94%, respectively. Under different hydroponic wastewater loading, the removal rates of pollutants were higher in the order of $75L\;m^{-2}day^{-1}{\fallingdotseq}150L\;m^{-2}day^{-1}$ $$\geq_-$$ $300L\;m^{-2}day^{-1}$. Therefore, optimum connection method was system A for treating hydroponic wastewater in greenhouse.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.5
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• pp.937-943
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• 2011

In order to develop constructed wetlands for treating hydroponic wastewater in greenhouses, removal efficiencies and decomposition velocities of pollutants in constructed wetland were investigated for treating hydroponic wastewater. Removal rates of BOD, COD, SS, T-N and T-P in effluent in constructed wetlands were 88%, 79%, 92%, 64% and 92%, respectively. The decomposition velocities (K; $day^{-1}$) of pollutants in $1^{st}$ HF bed of constructed wetlands were higher in the order of SS ($0.54day^{-1}$) > BOD ($0.39day^{-1}$) > COD ($0.27day^{-1}$) > T-P ($0.26day^{-1}$) > T-N ($0.06day^{-1}$). In $1^{st}$ HF bed of constructed wetlands, the decomposition velocity of SS was rapid than that for BOD, COD, T-N and T-P in constructed wetland for treating hydroponic wastewater. The decomposition velocity (K; $day^{-1}$) of pollutants in $2^{nd}$ HF bed of constructed wetland were higher in the order of T-P ($0.52day^{-1}$) > BOD ($0.28day^{-1}$) > COD ($0.15day^{-1}$) > T-N ($0.06day^{-1}$) > SS ($0.10day^{-1}$). In $2^{nd}$ HF bed of constructed wetlands, the decomposition velocity of T-P was rapid than that for BOD, COD, SS and T-N in constructed wetland for treating hydroponic wastewater.

• Environmental Engineering Research
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• v.17 no.1
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• pp.3-8
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• 2012

A scaled-up bioconversion of fishmeal wastewater (FMW) into liquid fertilizer was performed five times in a $1m^3$ reactor in order to examine the feasibility of commercialization. The importance of aeration was marked. Analyses indicated that dissolved oxygen (DO) level was closely related to the value of oxidation-reduction potential (ORP) and it was crucial to achieve high-quality liquid fertilizer. When pure oxygen was supplied through four diffusers into the reactor, DO levels and ORP values were maintained over 1.2 mg/L and 0.2 mV, respectively all the time during 52 hr of bioconversion. The pH changed from 6.8 to 5.9. The average removal percentages of chemical oxygen demand ($COD_{Cr}$) and total nitrogen (TN) were 75.0% and 71.6%, respectively. Compared to the result acquired in a 5-L reactor, bioconversion of FMW into liquid fertilizer was achieved in a shorter time under the same removal percentages of $COD_{Cr}$ and TN. The 52-hr culture of inoculated FMW was phytotoxic-free and it possessed comparable fertilizing ability to a liquid fertilizer made from the fish waste in hydroponic culture with amino acid contents of 5.93 g/ 100 g sample. From all the above results, transferring lab-scale data to large-scale production appeared to be successful. As a result, the commercialization of a liquid fertilizer made from FMW was feasible.

• Korean Journal of Environmental Agriculture
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• v.28 no.2
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• pp.171-178
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• 2009

Water shortages are expected to be a major impact of climate change. This study examined the growth of Chinese cabbage seedling using reclaimed wastewater and waste nutrient solution as alternative irrigation resources. Generally, the concentration of nutrients, such as $K^+$, $NH_4^+$, $Mg^{2+}$, $Ca^{2+}$, $Cl^-$,$NO_3^-$, $PO_4^-$ and $SO_4^{2-}$, in waste nutrient solution was higher than that in wastewater. However, Chinese cabbage seedling irrigated with wastewater was supplied a higher concentration of $Na^+$ and $Cl^-$ than waste nutrient solution. The growth of Chinese cabbage seedling irrigated with waste nutrient solution was similar or higher than those irrigated with groundwater as control, while the growth of those irrigated with wastewater was similar to those irrigated with groundwater. The total nitrogen uptake in Chinese cabbage seedling irrigated with groundwater, waste nutrient solution from organic and inorganic hydroponic cultures, and wastewater was 5.47, 10.02, 5.20, and 4.59 mg/plant, respectively. The nitrogen uptake of Chinese cabbage seedling irrigated with waste nutrient solution from organic hydroponic substrates in a 50% lower dose than recommended was 8.34 mg/plant, which is higher than that of the cabbage irrigated with groundwater. Overall, the results suggest that waste nutrient solution and wastewater can be used as alternate water resources, and can allow a reduction in the amount of fertilizer needed to raise Chinese cabbage seedling.

• Korean Journal of Environmental Agriculture
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• v.21 no.2
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• pp.122-129
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• 2002

The removal rate of heavy metals from the wastewater, the accumulation and translocation of heavy metals in plants after transplanting, and the responses of water celery growth with different wastewater treatments were investigated to determine the potential ability of green-remediation with hydroponic culture of water celery. The removal rate and translocation of Cd, Cu, Ni and Pb from different wastewater to plants were compared with cultivation periods after transplanting. The removal rate of heavy metals from wastewater was different with each treatment but increased with growing periods of water celery plants. The removal rate of Cd, Cu, Ni and Pb in Artificial solution, Artificial solution+EDTA, Munmark industrical wastewater, Jungsun minewater is ranged from 22 to 73%, from 28 to 100%, from 13 to 92% and from 41 to 100% at 6 days after transplanting, respectively. The translocations of Cd, Cu, Ni and Pb from roots to shoots in Artificial solution, Artificial solution+EDTA, Munmark industrical wastewater, Jungsun minewater are ranged from 14 to 28%. 8 to 30%. from 28 to 45% and from 2 to 15% at 12 days after transplanting, respectively. In plant growth responses, it appears to be inhibited the plant growth over all treatments excepts for Munmark industrial wastewater in these glowing periods. Therefore the water celery might play a useful role in phytoremediation to clean up wastewater contaminated with Cd, Cu, Ni or Pb.

• The Korean Journal of Ecology
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• v.15 no.2
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• pp.137-145
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• 1992

When exposed to 1, 700 ml of 0.089, 0.445 or 0.890 mM/l cadmius solution, dock (rumex crispus L)plants from heavily polluted chungrangchon site absorbed 0.0404, 0.2244 or 0.4929 mM of cadmium per g dw during the first 4 hours, which were 5.0~30.8 times faster uptake rate than those of water hyacinth (eichhornia crassipes Solm. - laub). Zinc, with which cadmium generally occurs together, did not affect the uptake rate in the concentration range of 0.0306 ~0.0918 mM/l. rumex cripus from chungrangchon site and from less polluted shingalchon site, when exposed to 1, 700 ml of 0.089 mM/l solution for 3 days, removed 68.4% and 63.2%, repectively, of the cadmium initially present in the solution. And when exposed to cadmium solution of the same concentration for the second time after cadmium-free hydroponic culture for three days, these plants removed 76.1% and 66.8% of cadmium, respectively. These removal rates were not significantly different between collection sites or between exposures, but were about 2 times greater for the first exposure, and 2~5 times greater for the second exposure, than those of water hyacinth. these results incate that rumex cripus can absorb, and thus remove, large amount of cadmium ion in wastewater, and so can be used in wastewater treatment, e.g. soil trench method. since there was large difference among the plants in the ability to absorb cadmium, it should be possible to select for strain with greater ability.

• Korean Journal of Environmental Agriculture
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• v.27 no.3
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• pp.217-224
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• 2008

To obtain optimum configuration, depth and load of constructed wetlands(CWs) for treating of hydroponic waste solution(HWS) which was produced in greenhouses, the study was conducted with 4 kinds of combined systems such as Vertical flow(VF)-Horizontal flow(HF), VF-VF, HF-VF and HF-HF CWs. In four configurations of CWs, the treatment efficiency of pollutants from HWS under depth of HF and VF beds, HWS loading and HWSs were investigated. Removal rate of pollutants under different depth of VF and HF in 2-stage hybrid CWs was in the order of 50 cm < 70 cm regardless of CWs configuration. Removal rate of pollutants under HWS loading in 2-stage hybrid CWs was in the order of $150L\;m^{-2}\;day^{-1}{\fallingdotseq}300L\;m^{-2}\;day^{-1}\;>\;450L\;m^{-2}\;day^{-1}$. The optimum depth and HWS loading were 70 cm and $300L\;m^{-2}\;day^{-1}$ in four configurations of CWs, respectively. Using this optimum condition, for various HWSs (cucumber, paprika and strawberry HWS), removal rate of pollutants in HF-HF CWs was higher than that in HF-VF CWs. Optimum configuration of 2-stage hybrid CWs for treating hydroponic waste solution in greenhouses was found out to be HF-HF CWs. Therefore, under the optimum conditions, removal rate of BOD, COD, SS, T-N and T-P in HF-HF CWs were 84, 81, 84, 51 and 93%, respectively.