Search

Micro-nano bubble, electro-oxidation and ozone treatment of wastewater is widely accepted. In this study the effect of these technologies as a pre-treatment process in removing fluoride was observed and compared. The wastewater from Kumho Petrochemical Co. Ltd. (final product is synthetic resins) containing BF 3 was infused with micro-nano bubble, electro-oxidation and ozone gas for 2 h and then pH adjustment was done by adding Ca(OH) 2 . PAC 11%, F900 and Alum were used after that and then polymer was added. The micro-nano bubble pre-treatment shows better removal percentages than those of electro-oxidation and ozone pre-treatment. The combination of F900 and A-polymer with micro-nano bubble pre-treated wastewater seems to have a higher fluoride removal percentage than the other combinations (76.7%) whereas without pre-treatment, the maximum fluoride removal percentage was observed to be 69.6%. %. Therefore, an increase of 7.1% was obtained over traditional treatment for air bubble pre-treatment. For electro-oxidation and ozone pre-treatment, fluoride removal percentages were somewhat within the same range with no pre-treatment values. In case of COD removal, the combination of F900 and A-polymer with micro-nano bubble pre-treated wastewater was observed to be the best (63.6%) whereas without pre-treatment, the maximum COD removal percentage was observed to be 54.9%. For electro-oxidation and ozone pre-treatment, COD removal percentage was found without the range of 31.4%–47.5%, which is even lower than without pre-treatment values.

Purpose: Methane production potential in aerobic digestion was assessed according to feed to inoculum (F/I) ratio for food waste only, and mixing ratio of two materials for food waste and swine manure to give a basic data for the design of anaerobic digestion system. Methods: Anaerbic digestion test was performed using a lab scale batch reactor at for six different feed to inoculum (F/I) ratios (0.50, 0.72, 1.14, 1.50, 2.14 and 3.41), three food waste to swine manure ratios (100:0, 60:40 and 40:60) with two different loading concentrations (10g VS/L and 30g VS/L). Results: For food waste only, the highest biogas yield of 1008 mL/gVS was obtained at 0.50 of F/I. For the co-digestion of food waste and swine manure mixture, the highest biogas yield of 1148 mL/gVS was obtained at a mixing ratio of 40:60 with loading concentration of 10g VS/L. Conclusions: F/I ratio for the food waste only, mixing ratio of food waste and swine manure, and co-substrate loading rate affected the biogas production rate. For the low loading rate, there was not so much difference according to the mixing ratio of food waste and swine manure, but for the high loading rate higher biogas yield was acquired for the co-digestion of food waste and swine manure than for the food waste alone (mixing ratio, 100:0).

Saururus chinensis is used as a raw material of an anti-rheumatic, poultice, sedative and stomachic. The tea of dried Saururus chinensis leaves has a function of relaxing pains in back and breast and of treating stomach ailments. The plant has the functions of anti-inflammatory, depurative, diuretic, febrifuge and refrigerant. The extraction of functional material is carried out by methanol and ethanol solvents. Mechanochemical grinding is applied as a pretreatment process before extraction to enhance the extraction efficiency by increasing the surface area of the materials while changing the chemical properties of the materials. Extraction of functional materials from the Saururus chinensis after grinding as a pretreatment using the mechanochemical technology was accomplished in this study to investigate the effect of grinding on the antioxidant activities of the extract. Saururus chinensis was ground by the planetary ball mill and the morphology was analyzed by SEM. Mechanochemical pretreatment increased the yields of functional materials from 5.9 g to 6.4, 7.0, and 8.1 g after grinding of 30 minutes, 1 hour and 2 hours, respectively. Nitrite scavenging ability increased from 53.0-71.0% to 61.0-79.0% for the methanol extraction in the solution of pH 1.2. Also, Electron donating abilities were increased from 7.90-33.51% to 11.97-38.51% for the methanol extraction. The extract concentration for the half inhibition of DPPH radicals was reduced from 278μg/mL in the original sample to 263μg/mL in the sample after grinding for the methanol extraction.

Houttuynia cordata is used as a raw material of oriental medicine to acquire antioxidant and anti cancer effect and to cure a heart disease. Mechanochemical technology not only reduces the size of the object but also changes the chemical properties of the object. Extraction of functional materials from the Houttuynia cordata after grinding as a pretreatment using the mechanochemical technology was conducted in this study to investigate the effect of grinding on the yields and antioxidant activities of the extract. Houttuynia cordata was ground by the planetary ball mill and the morphology was analyzed by SEM. Yields of functional materials were increased from 6.2 g in the sample without grinding to 7.0, 7.8, 8.8 g after grinding of 30 minutes, 1 hour and 2 hours, respectively. Nitrite scavenging abilities were increased from 57-77% to 69-86% as a result of mechanochemical pretreatment. Also, DPPH scavenging abilities for the methanol extraction were increased from 10.01-40.29% to 11.01-49.29% as a result of mechanochemical grinding.

The swine wastewater from Sunchon swine farm was decomposed using a sequencing batch reactor (SBR). The reactor body was fabricated using a plexi glass cylinder and its total volume was 20L with 15L of working volume. Each operating cycle consisted of five phases (fill, react, settle, draw and idle) with a total cycle time of 8 hours, thus resulting in three cycles per day (with 5 days of hydraulic retention time and 41 days of solid retention time). The cycles of the SBR system were controlled by a designed on-site computer and custom software. The results showed removal efficiencies of 85.5%, 80.3% and 87.2% for BOD, COD and TP respectively. It was found however that there were some non-satisfactory results, only attaining removal efficiencies of 61.0%, 31.2% and 54.5% for TN, NH 3 -N and NO 3 − -N respectively. This was possibly due to the lack of enough carbon source and the inadequate aeration rate. It was also observed that removal efficiencies of 61.4%, 62.8%, 77.6% and 73.2% could be obtained for TS, TVS, TSS and TVSS respectively. The study showed that the SBR system could be used to attain good removal efficiencies of BOD, COD and nutrients in swine wastewater treatment if it is supplied with sufficient carbon source for de-nitrification and optimum aeration for nitrification.

To ascertain the possibility of producing refuse derived fuel (RDF) using waste plastic film and sewage sludge, the current state of waste plastic film and sewage sludge generation was investigated and the heavy metal components and heating values for those materials were analyzed. At this time waste plastic film from agricultural production is being discarded in the fields and sewage sludge is being buried in landfills or discharged into the ocean, resulting in land and ocean pollution in Korea. Waste plastic film from mulching operations on farm land and sewage sludge could be used to produce RDF if they are mixed in the proper ratio to get the heating value required for standard RDF. The Hg, Cd, Pb and As content did not exceed the specified limits for RDF, demonstrating the usability of waste plastic film and sewage sludge as raw materials of RDF. From an elementary analysis of waste plastic film and sewage sludge, SO 2 gas is not expected to be discharged, while NO x gas may possibly be discharged in the flue. To get the heating value required for RDF, a mixture of 50% waste plastic film and 50% sewage sludge was desirable.

A 30 day laboratory scale experiment was carried out using three different aeration rates, i.e. +35 mV oxidation–reduction potential (ORP: standard hydrogen electrode), 1·0, and 3·0 mg[O 2 ] l −1 , to achieve solids decomposition and odour control in pig slurry with total solids (TS) levels from 0·5 to 4·0%. Changes during the aeration process were characterised by TS, total volatile solids (TVS), total suspended solids (TSS), and total volatile suspended solids (TVSS), all expressed as w/w. The measurement of volatile fatty acids (VFAs), expressed as w/v, was used to evaluate the potential odour generation in the aerated slurry. The TS removal efficiencies from 6·0 to 44·9, 18·6 to 50·3, and 42·3 to 56·4% were observed for the three different aeration levels, with reductions from 6·6 to 48·9, 26·0 to 61·1, and 57·3 to 69·9% for the slurry TVS. The ratios of TVS/TS, TSS/TS, and TVSS/TS in slurry over the experimental duration were found to increase with increased TS levels in the 30 day aeration under the three aeration intensities. Reductions in the 5 day biological oxygen demand (BOD 5 ) reached 78·5–92·0, 79·4–96·0, and 91·2–97·0%, while reductions of VFAs reached 12·7–99·0, 71·7–99·0%, and 87·8–99·3%. The biodegradation of solids, BOD 5 , and VFAs was effectively enhanced when aeration time and intensity were increased. A low level of solids in slurry promoted aerobic decompositions of solids, BOD 5 , and VFAs. Changes of state in the solids being aerated and changes in the BOD 5 levels can be used to distinctly characterise the potential of odour generation from the slurry. Batch aeration of 5–10 days under intensities of 1·0 to 3·0 mg[O 2 ] l −1 is recommended for odour control at farm level.

The purpose of this study is to quantify the thermal conductivity of sewage sludge related to reaction temperature for the optimal design of a thermal hydrolysis reactor. We continuously quantified the thermal conductivity of dewatered sludge related to the reaction temperature. As the reaction temperature increased, the dewatered sludge is thermally liquefied under high temperature and pressure by the thermal hydrolysis reaction. Therefore, the bound water in the sludge cells comes out as free water, which changes the dewatered sludge from a solid phase to slurry in a liquid phase. As a result, the thermal conductivity of the sludge was more than 2.64 times lower than that of the water at 20. However, above 200, it became 0.704 W/m* degrees C, which is about 4% higher than that of water. As a result, the change in physical properties due to thermal hydrolysis appears to be an important factor for heat transfer efficiency. Implications: The thermal conductivity of dewatered sludge is an important factor the optimal design of a thermal hydrolysis reactor. The dewatered sludge is thermally liquefied under high temperature and pressure by the thermal hydrolysis reaction. The liquid phase slurry has a higher thermal conductivity than pure water.

A 30-day bench-scale aeration experiment was carried out with three different aeration levels, i.e., +35 mV ORP, 1.0 mg O2 L-1, and 3.0 mg O2 L-1, to treat swine manure with solids levels from 0.5% to 4.0% for solids decomposition and odour control. Solids changes during the aeration process were characterized by total solids (TS), total volatile solids (TVS), total suspended solids (TSS), and total volatile suspended solids (TVSS). Volatile fatty acids (VFAs) was used to evaluate the odour generation potential in the aerated manure. The overall TS removal efficiencies from 6.0% to 44.9%, 18.6% to 50.3%, and 42.3% to 56.4% were observed for the three different aeration levels, respectively, with reductions from 6.6% to 48.9%, 26.0% to 61.1%, and 57.3% to 69.9% for manure TVS. The ratios of TVS/TS, TSS/TS and TVSS/TS in manure were found to increase with solids levels in the 30-day aeration process under the three aeration intensities. Reductions of BOD5 reached 78.5% to 92.0%, 79.4% to 96.0%, and 91.2% to 97.0%, while reduction of VFAs reached 12.7% to 99.0%, 71.7% to 99.0%, and 87.8% to 99.3%. The biodegradation of solids, BOD5, and VFAs was effectively enhanced when aeration length and level were increased. Low solids levels in manure offered a more advantageous condition for aerobic decompositions of solids, BOD5, and VFAs. Linear correlation analysis proved that the odour generation potential in manure being treated by aeration process could be distinctly characterized by the change of solids in different forms and/or by the BOD5 levels.

The influences of aeration rates (0.5, 1.2 and 1.9 L/M) for different temperatures (5, 15, and 25 oC) on the ammonia emission and the breakdown of organic material were studied for 21 days of biodegradation using 15.3 L of batch reactors. From 9.7 to 37.7 % of total Kjeldahl nitrogen was removed during the experiment with higher values for the higher manure temperatures and the higher aeration rates. From 0.7 to 25.8 % of initial TKN was volatilized as ammonia gas showing higher value according to manure temperature and aeration rate. The ratio of volatilized ammonia gas to the reduced TKN was from 6.5 to 68.5 showing also higher value according to manure temperature and aeration rate. BOD5 removal was also higher with the higher temperature and the higher aeration rates with the exception between 0.5 and 1.2 L/M for the manure of 5 and 15 oC. Higher aeration (1.9 L/M) for the lower temperature (5 oC), and lower aeration (0.5 L/M) for the higher temperature (15 – 25 oC) were desirable to reduce ammonia emission while satisfying BOD5 removal to a certain extent.

A bench-scale study on swine manure stabilization for odour control was conducted using batch aeration reactors. In trial 1, two aeration lengths, i.e., 0.5 and 4.0 day, were used under uncontrolled ambient temperature that increased gradually over the experimental period. While in trial 2, a 16.0-day aeration scheme was employed under constant 17 °C. An airflow rate of 1.2 L/s/m 3 was used for both trials to aerate batch reactors containing finishing pig manure with initial total solids (TS) levels ranging from 0.5 to 4.0%. Manure stabilization during the 90-day post-treatment storage was evaluated by the changes in organic materials, nitrogen and volatile fatty acids (VFA). The odour generation potential in the treated manure was determined by the changes in VFA. Up to 827 mL of liquid was lost due to aeration related foaming. The reductions in total volatile solids (TVS), 5-day biochemical oxygen demand (BOD 5 ), total Kjeldahl nitrogen (TKN) and VFA during storage were improved when aeration length increased. Low solids levels offered a more advantageous circumstance for manure stabilization and odour control. Biodegradation of organic matter, removal of nitrogen, and breakdown of VFA would increase with increasing ambient temperature. VFA removals in manure under 16.0-day aeration were higher than those under 0.5- and 4.0-day aeration; however, VFA regeneration started to exceed its consumption on day 20 (4 days after the aeration treatment). BOD 5 was the best estimate of VFA concentration in the aerated manure during storage. The 4.0-day aeration scheme was sufficient to stabilize manure to effectively assuage odour generation potential during the 90-day storage under increasing ambient temperature conditions.