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효율적인 산업규모의 폐수처리 정보

작성자 일산실업(주) | 작성일시 2015-05-22 16:37 | 조회 1,732
1. Effective Chemical Treatment of Biologically Treated Distillery Wastewater in Industrial Scale





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Ki-Du Nam·In Chung*·Daniel Hur* and Wan Park** Il San Trading Co., Ltd, Pusan 608-044. Korea, 1Jindo Co., LTD. R & D Ceenter 2Department of Microbiology, College of Natural Sciences Kyungpook National University, Teagu 702-701, Korea


ABSTRACT


For further removal of non-biodegradable CODs and color in biologically treated distillery waster water, we selected a chemical treatment with Fe(III) and cationic polymers and then another chemical treatment with Fenton reagent. We developed Pregenerated Bubble Flotation(PBF) to effectively remove the chemical sludge from each chemical reaction process. The flotation unit was constructed with hydraulic loading rate, 7 m3/m2/hr. In general, solid loading rate for Dissolved Air Flotation(DAF) sludge thickening with coagulants are recommended to be 6-12 kg/m2/hr. PBF, however, could handle solid loading rate of 10.8-14.5 kg/m2/hr. The CODMn and suspended solids(SS) in biologically treated distillery waste water were reduced by the first PBF from 310-1096 mg/L to 141-303 mg/L and from 160-990 mg/L to 48-385 mg/L, respectively. Again, after the Fenton reaction process, floated SS was skimmed off at the top of the flotation unit and the final effluent was directly discharged without any tap water dilution. The quality of final effluent can be below 40 mg/L-CODMn but Il San Distillery has been maintained effluent quality of 73 mg/L-CODMn and 10-80 mg/L-SS. The chemical cost was saved by more than 30 % as compared with that of prior process.

Key words : non-biodegradable, pregenerated bubble flotation(PBF), Fenton reaction, distillery wastewater, chemical treatment






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2. TREATMENT  OF DISTILLERY  WASTEWATER     Ⅰ
A THERMOPHILIC HIGH RATE ANAEROBIC REACTOR OPERATION EXPERIENCE

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Ki-Du Nam, Il-San Trading Co., LTD.  Pusan, Korea E-mail: Lab7394@chollian.dacom.co.kr, Wan
Park, Department of Microbiology, Kyungpook National University, In Chung, Jindo Engineering and
Construction Co., LTD., Research Center, 371-62, Kasan-Dong,  Kumchon-Ku, Seoul, 153-023, Korea
E-mail: wweksh@chollian.dacom.co.kr

There are 12 distilleries in Korea and 11 of them have fermentation processes to produce alcohol. The 11 distilleries use naked-barley, barley, rice, tapioca, sweet potato, potato, and corn as raw materials. All 11 distilleries at one time operated thermophilic anaerobic digesters having hydraulic retention times (HRT) of 15 to 45 days followed by aerobic treatment of the anaerobic effluent. All 11 distilleries experienced numerous reactor failures when treating naked-barley wastewater anaerobically. In one case, a digester operating at a 36-d HRT failed after receiving naked-barley wastewater for 15 days continuously. Korean distilleries have not reported any specific difficulties with anaerobic treatment of wastewater from fermentation of other raw materials except naked-barley. Comparing various options for treating distillery wastewater, Maiorella et al.(1983) concluded that evaporation for cattle feed production was the most attractive option for grain distillery wastewater. The capital costs estimated by Maiorella et al.(1983) were 3 million US dollars for evaporation and 3.5 million US dollars for anaerobic treatment. In Korea, however, the capital cost associated with evaporation of 300 m3/d of distillery wastewater is about 3.9 million US dollars while the capital cost for anaerobic reactor installation is about 1.0 million US dollars. These estimates do not include the cost for aerobic treatment that should follow both evaporation and anaerobic treatment. However, Korean distilleries having fermentation processes are required to use some amount of naked-barley as raw material and were very tired ofanaerobic reactor failures that occurred during the continued use of naked-barley for fermentation. Therefore, 6 of 11 distilleries are currently either operating or constructing evaporators, giving up the more economical option of anaerobic treatment. The characteristics of distillery wastewater produced in Korea vary widely and total suspended solids (SS) concentrations in the raw wastewater typically average 25,000 to 100,000 mg/L. Usually, decanters (centrifuges) are used to remove as much of SS from the raw wastewater as possible and the decanter effluent is treated anaerobically. The characteristics of decanted distillery wastewater typically are as follows ; pH = 3.5 to 4.5, temperature = 70 to 80oC, soluble Chemical Oxygen Demand (sCOD) = 25,000 to 60,000 mg/L, total COD (tCOD) = 40,000 to 100,000 mg/L and TSS = 4,000 to 20,000 mg/L. Prior to May 1995, the Il-San distillery in Pusan, Korea produced 50 m3/d of 95% ethanol and the flow rate of decanted wastewater was 400 m3/d. Two thermophilic anaerobic digesters having a total effective volume of 6,000 m3 (digester #1 with 4,000 m3 and digester #2 with 2,000 m3) were employed for anaerobic treatment. An anaerobic settling tank received the effluent from the digesters and settled SS were recycled to the digesters. An induced air flotation (IAF) unit received the settled wastewater and further removed SS with polymer addition. A conventional activated sludge tank with 1,500 m3 effective volume was used to treat the IAF effluent. Since the sCOD removal efficiency of anaerobic treatment was not high enough, 1:1 dilution with tap water was required for successful aerobic treatment. A settling tank was used to settle the activated sludge, and the settling tank effluent was treated chemically to remove as much caramel color as possible. Chemically treated wastewater went through another settling tank and then was discharged.
The COD removal efficiency of Il-San's digesters (and other distilleries ◎digesters in Korea) was about 50 to 70%. The operators in Il-San distillery wanted to increase the efficiency of anaerobic treatment and hoped to operate anaerobic reactor(s) without any influence of toxicity when treating naked-barley wastewater. In addition, they wanted to stop using dilution for aerobic treatment. In order to solve the above problems, Il-San's digester #2 was converted to a thermophilic high-rate hybrid anaerobic reactor. The hybrid reactor has been operating successfully since May 1995, at loading rates of 5.45 to 15.02 kg/m3/d. The hybrid reactor has demonstrated sCOD removal efficiencies of 85 to 91% and tCOD removal efficiencies of 72 to 84%. Total COD removal rates were 4.31 to 5.43, 6.26 to 6.89 and 9.03 to 9.78 kg tCOD/m3/d for tapioca, corn, and naked-barley wastewater, respectively. Soluble COD removal rates ranged from 3.75 to 4.79, 3.28 to 4.89 and 5.57 to 6.21 kg sCOD/m3/d for tapioca, corn, and naked-barley wastewater, respectively. The product gas had a methane content of 59 to 68%. When treating naked-barley wastewater, the gas production rate averaged 6.61 to 7.57 m3/m3 reactor/d and produced 0.57 to 0.69 m3biogas/kg tCODrem. (at standard conditions of 0oC and 1atm). When treating tapioca and corn wastewater, the reactor showed average gas production rate of 0.53 to 0.69 and 0.62 to 0.71 m3/kg tCODrem. (at standard conditions of 0oC and 1atm), respectively. Gas production rates ranged from 3.18 to 3.46 and  4.91 to 5.22 m3/m3 reactor/d for  tapioca and corn wastewater, respectively. The hybrid reactor was capable of handling very high SS input and demonstrated SS removal efficiencies of 9 to 16, 35 to 49, and 60 to 71% for tapioca, corn, and naked-barley wastewater, respectively.



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3. TREATMENT  OF DISTILLERY  WASTEWATER     Ⅱ
CHEMICAL TREATMENT AFTER BIOLOGICAL TREATMENT



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Ki-Du Nam, Il-San Trading Co., LTD.  Pusan, Korea E-mail: Lab7394@chollian.dacom.co.kr,
Daniel Hur, Jindo Eng. and Const. Co., LTD., In Chung, Jindo Engineering and Construction Co.,
LTD., Research Center, 371-62, Kasan-Dong,  Kumchon-Ku, Seoul, 153-023, Korea E-mail:
wweksh@chollian.dacom.co.kr

After start-up of thermophilic high-rate anaerobic reactor, aerobic treatment efficiency was stabilized and aerobically treated and then settled effluent (biologically treated distillery wastewater) quality was 600~1020 mg CODCr/L (300~550 mg CODMn/L), 50~90 mg BOD/L and 350~450 in color unit. Respirometer testing of biologically treated distillery wastewater revealed that these BODs were mostly nitrogenous oxygen demand. That is, Il-San's anaerobic + aerobic treatment system did remove most of the biologically removable organics and the CODs and color in biologically treated distillery wastewater were non-biodegradable. Chemical treatment of biologically treated distillery wastewater was very costly and therefore, Il-San operators had to use 1:1 dilution with tap water plus chemical treatment in order to match effluent regulations. Thus Il-San operators wanted to eliminate 1:1 dilution and wanted to cut
down chemical treatment cost while the effluent quality could be comfortably under the regulatory limit of 120 mg CODMn/L.
Since most of COD in  biologically treated distillery wastewater was non-biodegradable, further biological treatment was not considered. Many different chemical treatment methods were investigated and as a result, chemical treatment with Fe(III) and anionic polymer and then another chemical treatment with H2O2 + Fenton reagent were selected as the best option because of their performance and economics. Between chemical reaction processes, chemical sludge should be removed very effectively since the space for new reactors, sedimentation tank or Dissolved Air Flotation (DAF) tank was very limited. That is, any process that would
be used should be very compact and efficient in order to achieve the above goals. First of all, DAF testing was performed but specific gravity of chemically treated sludge was found to be too high for DAF air bubbles. Therefore, a very innovative technique named Pregenerated Bubble Flotation (PBF) was developed to produce very fine (20~50㎛ in diameter compared to regular DAF bubbles with 80~120㎛ in diameter) bubbles with very actively charged surfaces. The bubbles generated had very strong chemical adsorbability to suspended solids (SS) and were very effective to remove chemically treated sludges and SS. In addition, PBF bubbles were able to remove 10~70% of dissolved solids (DS). The removal efficiency of DS varied with wastewater and chemical additives used for generate pregenerated bubbles.



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3. TREATMENT OF DISTILLERY WASTEWATER  
EVALUATION OF EXTERNAL CARBON SOURCES FOR HIGHLY EFFICIENT
BIOLOGICAL DENITRIFICATION




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Sun-Jip Kim, JINDO Engineering and Construction Co., Ltd., Research Center, 371-62, Kasan-Dong,
Kumchon-Gu, Seoul, 153-023, Korea. (E-mail: research @ jindoec.co.kr), Duk Chang, KON-KUK
University, Soon-Ho Lee, JINDO Eng. & Const. Co., Ltd., Ki-Du Nam, ILSAN Trading Co., In
Chung, JINDO Eng. & Const. Co., Ltd.


Deterioration of water environment has provoked nitrogen removal of grain distillery wastewater. For this reason, DeNitro/JIN( system, of which concept is seperating the growth environment of nitrifiers and denitrifiers, was developed for high-nitrogen-content wastewater. One of the important factors for denitrification is C/N ratio. The C/N ratio of anaerobic effluent, influent of biological nitrogen removal process(DeNitro/JIN(), is too low for high efficient denitrification. Finding of proper external carbon source is imminent for high efficient denitrification. Centrifugal decanter effluent(CDE) of distillery wastewater and impurity alcohol which is produced as a by-product during the distillation were evaluated as external carbon sources for biological denitrification of distillery wastewater. Influent characteristics of DeNitro/JIN( system are as follows; pH 7.0(8.25, Alkalinity 2,200(3,400mg/L as CaCO3, BOD 570(1,980mg/L, TKN 380(1,320mg/L. The C/N ratio of the influent fluctuated according to raw materials for fermentation, yield of fermentation and efficiency of alcohol recovery. The C/N(based on BOD) ratio averaged 1.19(0.45(2.06) for tapioca wastewater, 2.13(0.99(3.27) for tapioca and naked-barley mixed wastewater, and 1.51(1.26(2.02) for tapioca and barley mixed wastewater.

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