Decomposition of humic acid in effluents from Jokaso ( in Japanese, on-site
domestic wastewater treatment facility) by using of Ozone oxidation, Ultraviolet (
UV) ...
Sengupta, M. and Dalwani, R. (Editors). 2008 Proceedings of Taal 2007: The 12th World Lake Conference: 2173-2176
Treatment of the Humic Substance from a Domestic Wastewater Treatment Device Effluents M. Asano*, R. Hinokio1, F. Jiku1 and K. Saito1, Faculty of Science and Technology, Ryukoku University, Seta Oe, Otsu, Shiga, 520-2194, Japan Fuji Clean Industry Co., 4-1-4 Imaike, Chikusa-ku, Nagoya, Aichi, 464-8613, Japan *Corresponding author; E-mail:
[email protected]
ABSTRACT Decomposition of humic acid in effluents from Jokaso ( in Japanese, on-site domestic wastewater treatment facility) by using of Ozone oxidation, Ultraviolet (UV) irradiation, Ozone oxidation and UV irradiation (Ozone/UV) were investigated. From the results, CODCr, CODMn and humic acid in effluents were efficiency removed by using of Ozone/UV treatment. As for the removal of TOC by using of Ozone/UV treatment, there was a different trend between Jokaso A and Jokaso B. This difference was thought to come from wastewater treatment system. Therefore, we have thought that it was important to discuss about best combinations of biological wastewater treatment system and Ozone/UV treatment system. Keywords: Jokaso, COD (Chemical Oxidation Demands), TOC (Total Organic Carbon), Humic acid, Ozone, UV, Ozone/UV
INTRODUCTION Lake Biwa is largest lake in Japan. The area of this lake is 670.25 km2. And reservoir volume of this lake is 275 hundred million cubic meter. As for water quality of Lake Biwa, BOD (Biochemical Oxidation Demand), total phosphorus and total nitrogen have been improved by means of the progress of water treatment technology or enforcement of policy for improvement of lake water quality. However, COD (Chemical Oxidation Demand) has not been improving (Tomita 1993). Substances which are resistant to microbial degradation and escaped from domestic wastewater treatment plant have been suggested to cause hard improvement of COD in lake water. Humic acid has been thought as one of these substances. Humic acid is difficult to remove by use of biological wastewater treatment system such as activated sludge wastewater treatment technology. In Japan, domestic wastewater in urban area have been treated with sewage treatment system. And domestic wastewater in rural area has been treated with domestic wastewater treatment system such as Jokaso. However, both wastewater treatment system are mainly used for biological wastewater treatment system. So non-biodegradable substances such as humic acid have been contained in effluent from both wastewater treatment system. Therefore, it is necessary to develop the on site wastewater treatment technology for the removal of non-biodegradable substances. In recent years, Advanced Oxidation
Process (AOPs) such as Ozone oxidation and Ozone oxidation and UV irradiation (Ozone/UV) and so on have been studied for application of wastewater treatment technology for the removal of nonbiodegradable substances (Somiya 1989, Takahashi 1993). In this study, we have investigated to treat effluent from Jokaso by using of Ozone oxidation, UV irradiation and Ozone/UV as a view point of COD removal. METHODS Effluent from Jokaso We have collected effluent from 2 types of Jokaso. Effluent which was collected from Jokaso A has been treated by using of activated sludge wastewater treatment system under long time aeration. Jokaso A has been targeted for wastewater treatment for 10 persons scale. On the other effluent from Jokaso B has been treated by using of biofilm wastewater treatment system under contact aeration. Jokaso B has been targeted for wastewater treatment for 500 persons scale. Apparatus Figure 1 is a schematic diagram of the Ozone/UV treatment apparatus. This apparatus composed from 5L of pyrex glass reactor, teflon magnet pump for circulating waste water (4L/min, IFP-111, Sanso Co.,
Japan), ozone generator (ED-OG-R3Lt, Eco Design, Japan), ozone gas monitor (EG-550, Ebara industry Co., Japan), low pressured immersion UV lamp (254nm, 30W, TNN 30/80, Heraeus Co., Germany), DC power supply for UV lamp (NV-2F, Mitsubishi Co., Japan), gas dryer (DH-106-1, Komatsu Electronics Co., Japan), air pump (6-7L/min, BA106TN-07).
minutes. It was suggested that the non-degradable substances such as humic acid was decomposed into low molecular weight substances which was able to detect by CODCr analysis. The efficiency of CODCr removal in effluent was most remarkable by use of ozone/UV treatment. Moreover Figure 3, humic acid were found to decrease remarkably by using of Ozone oxidation or Ozone/UV treatment. But for UV irradiation treatment, the removal of humic acid was not effective. On the other hand, the removal of TOC was found clearly by using of Ozone/UV treatment in Figure 4. The removal rate of CODCr were 1730% (Ozone oxidation), 13-19% (UV irradiation) and 91-97% (Ozone/UV). As for removal of humic acid were 59-60% (Ozone oxidation), 13-19% (UV irradiation), 70-76% (Ozone/UV). And more removal of TOC were 0% (Ozone oxidation, UV irradiation), 64-68% (Ozone/UV). From these results, it was supposed that substances which are resistant to microbial degradation such as humic acid were removed efficiency by use of Ozone/UV treatment.
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Figure 1: Schematic diagram of Ozone/UV treatment system
Experimental procedures Ozone/UV treatment of effluent from septic tanks were examined under about 10g /m3 of ozone gas supply and 254 nm of UV irradiation. 150mL of water samples were collected from the reactor for CODCr (Standard Method 5220D), CODMn and BOD and humic acid (Sewer Test Method, Japan), TOC (TOC Vscn, Shimadzu Co. Japan) analysis. First, 150mL of water was collected for initial condition analysis. After sampling, the ozone gas supply and DC power supply were turned on to start the experiment. Moreover, ozone oxidation treatment or UV irradiation treatment of effluent from Jokasos were used Ozone/UV treatment apparatus under each system (Ozone oxidation or UV irradiation) only. 150mL of water samples were collected frequency during 45 minutes. RESULTS AND DISCUSSIONS Treatment of effluent from Jokaso A Figure 2,3,4 shows removal of CODCr, humic acid, TOC from effluent by using of Ozone oxidation, UV irradiation, Ozone/UV treatment. In Figure 2, CODCr were found to increase temporarily in ten
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CODCr (mg/L)
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Figure 2: Removal of CODCr in effluent from Jokaso A by use of each treatment.
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Humic acid (mg/L)
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Figure 3: Removal of humic acid in effluent from Jokaso A by use of each treatment
were not shown), ratios were decreased 15% (Ozone/UV) and 11% (Ozone oxidation). But for UV irradiation, the ratio was increased 28%. Moreover, removal of BOD were found to decrease gradually between Ozone oxidation, UV irradiation, Ozone/UV treatment (Figure 8). From these results, substances which are resistant to microbial degradation such as humic acid were supposed to be removed by use of Ozone oxidation or Ozone/UV treatment. However, it was thought that humic acid were decomposed into low molecular weight substances. As for the removal of TOC by use of Ozone/UV treatment, there was a different trend between septic tank A and septic tank B. This difference was thought to come from wastewater treatment system. Therefore, we have thought that it was important to discuss about best combinations of biological wastewater treatment system and Ozone/UV treatment system.
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TOC (mg/L)
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Ozone oxidation UV irradiation CODMn (mg/L)
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Figure 5: Removal of CODMn in effluent from Jokaso B by use of each treatment:
Figure 4: Removal of TOC in effluent from Jokaso A by use of each treatment 20
Treatment of effluent from Jokaso B 15 Ozone oxidation Humic acid (mg/L)
Figure 5,6,7,8 shows removal of CODMn, humic acid, TOC, BOD from effluent by use of Ozone oxidation, UV irradiation, Ozone/UV treatment. In Figure 5, CODMn were found to decrease gradually by use of Ozone oxidation or UV irradiation. About Ozone/UV treatment, the removal of CODMn was remarkableness. And in Figure 6, removal of humic acid were found clearly by using of Ozone oxidation and Ozone/UV treatment. However, removal of TOC were found to level off between Ozone oxidation, UV irradiation, Ozone/UV treatment (Figure 7). As for ratio of humic acid account for CODCr (data
UV irradiation Ozone/UV 10
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Figure 6: Removal of humic acid in effluent from
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Jokaso B by use of each treatment
REFERENCE
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TOC (mg/L)
15 Ozone oxidation UV irradiation Ozone/UV 10
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Figure 7: Removal of TOC in effluent from Jokaso B by use of each treatment
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15 Ozone oxidation BOD (mg/L)
UV irradiation Ozone/UV 10
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Figure 8: Removal of BOD in effluent from Jokaso B by use of each treatment
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Shigeyuki Tomita, (1993): Humic substances and the growth of phytoplankton (1), Movement of humic substances in Sera River and Lake Biwa southern lake, in Japanese Isao Somiya, (1989): Ozone applicatory water treatment technology, Environmental Pollution Control Technology, in Japanese Nobuyuki Takahashi, (1993): Decomposition of nonbiodegradable organic substances by use of ozone, in Japanese Takeo Ishii and Shinichi Yoneuchi, (1990): New technology of ozone utilization, in Japanese, Sanshu Books APHA, AWWA, and WEF, (2005).”Standard methods for the examination of water and waste water (20th edition): 5220 D. Closed Reflux, Colorimetric Method” (1015 Fifteenth Street, NW, Washington, DC (2005), American Public Health Association Japan Sewage Work Association, (1997): Sewer test method, in Japanese (2005)
