• Korean Journal of Soil Science and Fertilizer
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• v.50 no.5
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• pp.489-496
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• 2017

This study was conducted to test the applicability of hydroxy radical reactor system, which applied advanced oxidation processes, to sterilize pathogenic bacteria for nutrient solution recycling in closed hydroponics. Removal efficiency was tested on 25 L of nutrient solution maxed with 10 mL culture solution of bacteria, E. coli, and R. solanacearum in a pilot tank. The testing conditions included various levels of hydroxy radicals resulting from air flow rates of 40, 80, and $120L\;min^{-1}$, and 12 hours processing time. The removal of bacteria, E. coli, and R. solanacearum by hydroxy radical in nutrient solution was significantly increased with an increase in the flow rate of the air from $40L\;min^{-1}$ to $120L\;min^{-1}$. The optimum removal efficiency was achieved at an air flow rate of $120L\;min^{-1}$ for 2 hours treatment. There were no significant differences in removal efficiency among bacteria, E. coli, and R. solanacearum for tested level and time of hydroxy radical. These results verified the efficiency of hydroxy radical in removing the pathogenic bacteria and the applicability of hydroxy radical reactor system in the field.

• Journal of Bio-Environment Control
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• v.12 no.2
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• pp.89-94
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• 2003

This study was conducted to identify the effect of recycling method of drained solution on the concentration of drained solution, and growth and yield of tomato in the recycling system. The recycling methods of drained solution were composed of control, MEC (measurement of EC) and ANS (analysis of nutrient solution). The plant height in the early growth stage was not different among the treatments, but plant fresh weight and dry weight were higher in the MEC or the ANS than in the control. The growth including fruit number, fruit weight, and yield of tomato in the ANS as compared with the control was favorable. The EC of drained solution tended to decrease in the early growth stage, but that of drained solution increased in the late growth stage. It was low in the MEC and the ANS as compared with the control. The pH of drained solution was maintained by 6.2 to 6.5 throughout the growth period in the MEC and the ANS, but the pH of the control increased up to 7.2 at the late growth stage. The N and K concentrations of drained solution tended to decrease in the early growth stage, while those of P, Ca and Mg increased. In the late growth stage, concentrations of N, P, Ca and Mg tended to decrease, but that of K in the ANS was very low. Concentrations of N, P, K, Ca and Mg were lower in the MEC and the ANS than in the control.

• Korean Journal of Soil Science and Fertilizer
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• v.37 no.3
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• pp.177-183
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• 2004

The discharge of waste nutrient solution from greenhouse to natural ecosystem leads to the accumulation of excess nutrients that results in contamination or eutrophication. There is a need to recycle the waste nutrient solution in order to prevent the environmental hazards. The amount and kind of nutrients in waste nutrient solution might be enough to grow photosynthetic microorganisms. Hence in the present study, we examined the growth and mass cultivation of cyanobacteria in the waste nutrient solution with an objective of removing N and P and concomitantly, its mass cultivation. Four photosynthetic filamentous cyanobacteria (Anabaena HA101, HA701 and Nostoc HN601, HN701) isolated from composts and soils of the Chungnam province were used as culture strains. Among the isolates, Nostoc HN601 performed faster growth rate and higher N and P uptake in the BG-II ($NO_3{^-}$) medium when compared to those of other cyanobacterial strains. Finally, the selected isolate was tested under optimum conditions (airflow at the rate of $1L\;min^{-1}$. in 15 L reactor, initial pH 8) in waste nutrient solution from tomato hydroponic in green house condition. Results showed to remove 100% phosphate from the waste nutrient solution in the tomato hydroponics recorded over a period of 7 days. The growth rate of Nostoc HN601 was $16mg\;Chl-a\;L^{-1}$ in the waste nutrient solution from tomato hydroponics with optimum condition, whereas growth rate of Nostoc HN601 was only $9.8mg\;Chl-a\;L^{-1}$ in BG-11 media. Nitrogen fixing capacity of Nostoc HN601 was $20.9nmol\;C_2H_4\;mg^{-1}\;Chl-a\;h^{-1}$ in N-free BG-11. The total nitrogen and total phosphate concentration of Nostoc HN601 were 63.3 mg N gram dry weight $(GDW)^{-1}$ and $19.1mg\;P\;GDW^{-1}$ respectively. Collectively, cyanobacterial mass production using waste nutrient solution under green house condition might be suitable for recycling and cleaning of waste nutrient solution from hydroponic culture system. Biomass of cyanobacteria, cultivated in waste nutrient solution, could be used as biofertilizer.

• Journal of Bio-Environment Control
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• v.8 no.3
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• pp.172-182
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• 1999

Leaf lettuce(Lacaug sativa L.) was cultivated in deep flow culture to investigate growth and yield in relation to different reusing method of nutrient solution after once cultivation. Five different treatments were allocated to the nutrient solutions - Control(total renewal of solution), NSS(nutrient solution supplement), U control, NSAC(nutrient solution analysis and compensation), NSAC and Humus supply(NSAC with supply of Humus). The pH of solution was kept stable below 7.0 during 4 successive culture in NSAC and NSAC and Humus supply. U was sharply declined in NSS as the number of cultivation was increased. Gmwth and yield of NSAC was similar to those of Control because nutrient elements were kept the balance to the better growth, while the lettuce grown in NSS and EC control was shown lower growth rate. In the nutrient solutions, Content of N $O_3$-N and N $H_4$-N were remarkably decreased after the cultivation in all treatments. Ca and Mg were shown to be accumulated in nutrient solution regardless of culture times and treatments. After the first culture in NSAC and Humus supply, total N and P$_2$ $O_{5}$ content in leaves were lower than any other treatments, but Ca content was higher. Those were not significant as following cultures, and no significant difference of K and Mg content were shown among the treatments.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• v.11 no.2
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• pp.227-230
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• 2006

• Journal of Energy Engineering
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• v.29 no.3
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• pp.34-41
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• 2020

Used disposable diapers have been considered for a long time as a type of waste difficult to recycle and valorize due to their composite nature including plastic, cellulose pulp, a super absorbent polymer and either urine, feces or both. Therefore, the fate of disposed diapers often is either incineration or landfill burial which both have various adverse environmental impacts. However, used disposable diapers contain nutrients: cellulose is an organic matter while urine and feces contain non negligible amounts of nitrogen, phosphorus and potassium which are primary nutrients included in most chemical fertilizers used in agriculture. In a scope of waste recycling and valorization, this study focuses on developing a method to achieve nutrient solution extraction from used disposable diapers. The experiment essentially consists in shredding the diapers and letting them macerate in solutions of sodium hydroxide with various concentrations to allow breaking down of the cellulose and super absorbent polymer and release of urine and feces before sterilizing the solutions in an autoclave to remove potential coliform bacteria. At the end of the experiment, a set of parameters is measured for the final solution to identify concentrations of nutrients as well as presence or absence of harmful substances. Results are discussed and directions for future studies are suggested, which include mechanization of the diapers shredding process or added aeration to enhance nitrification and absorption of extracted nutrients from plants.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.584-590
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• 1993

The constructed closed recycling system discussed in this technical report will be economically viable in future for the production of fish and vegetable in earth, space station and space colony, further, it will contribute a lot in the prevention of pollution in the world's ecological system. To make combined system, water management (Nitrification) is required, and it took 45 days to breed microorganism which facilitates this process. After this period , the recycle was confirmed to be working .Using derived equations, the expected nutrient characteristics of waste water were determined and it was found that the resulting nutrient balance was almost same as that in hydroponic solution when KOH was added to maintain pH level. Reverse osmosis (RO) system could solve the problem of the low nutrient concentration . It was found that plants grow well in fish waste water which was produced using RO system. RO system could combine fish and plant production through the advantageous use of separated high concentration water for plant and permeated water for fish in integrated combined system.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.6
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• pp.1300-1305
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• 2011

The study was conducted to investigate the characteristics of flower quality and yield of gerbera 'Sunny Lemon' by mutrient solution strength and media of nutrient solution. The plant growth of 'Sunny Lemon' showed the highest values in the media of rockwool and perlite 1: peatmoss 2. Especially the yield of cut flowers for a year was more than 60 flowers and the flower longevity was over 10 days irrespective of nutrient solution concentration in the two media. There were no significant differences of plant characteristics in the nutrient concentration of 1/2 and 1 times, and the mineral nutrient contents showed similar values. Therefore, we recommended the media of perlite1: peatmoss2 with the concentration of 1/2 times for economical use. The rockwool media was not appropriate because of the weak buffer capacity like EC and pH.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• v.11 no.2
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• pp.221-226
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• 2006

• Journal of Bio-Environment Control
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• v.18 no.4
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• pp.363-369
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• 2009

This experiment was conducted to find out the effect of nutrient solution composition on the growth of cucumber plants and the changes in macro-elements in nutrient solutions in recirculating hydroponic systems. Cucumber plants (Cucumis sativus L. cv. Joeun Baegdadagi) were grown in closed perlite cultivation systems supplied with different nutrient solutions developed by NHRS (National Horticultural Research Station in Japan), Yamasaki, PBG (Proefstation voor Bloemisterij en Glasgroente), and NIHHS (National Institute of Horticultural and Herbal Science in Korea). The concentrations of $NO_{3^-}N$, $Ca^{2+}$, $Mg^{2+}$, and $SO_{4^-}S$ in the recycled nutrient solutions increased but that of $NH_{4^-}N$ decreased gradually in all the treatments. The $PO_{4^-}P$ and $K^+$ concentrations were continuously reduced from the beginning of the harvest to the harvest peak period. There were no significant differences in the concentrations of $NO_{3^-}N$, $NH_{4^-}N$, and $Ca^{2+}$ in the recirculated nutrient solutions among four treatments, while the concentrations of $PO_{4^-}P$ and $K^+$ were lowest and those of $Mg^{2+}$ and $SO_{4^-}S$ were highest in the treatment of Yamasaki's nutrient solution. All growth-related parameters of cucumber plants except for leaf number were not significantly affected by the nutrient solution compositions. Due to its low concentrations of $PO_{4^-}P$ and $K^+$ in the recycled nutrient solution, however, the number and yield of cucumber fruits were lowest in the treatment of Yamasaki's nutrient solution.