• Journal of Korean Society of Water and Wastewater
• /
• v.18 no.3
• /
• pp.331-336
• /
• 2004

The correlation between polymeric aluminum species of coagulant and its coagulation efficiency was investigated using several commercial polymeric Al(III) inorganic coagulants (Poly Aluminum Hydroxy Chloro Sulfate 2020 (PAHCS2020), Poly Aluminum Hydroxy Chloro Sulfate 2500 (PAHCS2500) which was introduced in Korean water treatment plants. The poly aluminum chloride (PAC), Poly Aluminum Hydroxide Chloride Silicate (PACS)) and the aluminum salts ($AlCl_3$, Alum ($Al_2(SO_4)_3$)) were used for the purpose of comparison. The comparison of the coagulation efficiency of each coagulant was made by turbidity removal through the standard jar testing procedure and the determination of the hydrolytic Al(III) species was made by the ferron method which can differentiate the monomeric aluminum species from the polymeric aluminum species. Overall, PAHCS2020 and PAHCS2500 showed the better performance in turbidity removal than the aluminum salts. The performance of coagulation was even better without adjustment of pH during the coagulation experiment. The positive correlation between polymeric aluminum species of coagulant and coagulation efficiency was found.

• Journal of Korean Society on Water Environment
• /
• v.30 no.5
• /
• pp.532-538
• /
• 2014

A cylinder-shaped filter was developed to manage the runoff from construction sites. Compressed air was used for back-washing and pore sizes of filter were $23{\mu}m$ and $46{\mu}m$. The turbid water was prepared using sediments in construction sites. The grain size analysis showed that grains smaller than $38{\mu}m$ and larger than $335{\mu}m$ in size constituted 34.4 % and 37.6 %, respectively. Removal efficiency of the filter on turbidity, SS, COD, TN and TP showed 25~37%, 20~40%, 50~55%, 23~27% and 14~20%, respectively, whereas their removal efficiecy by using coagulant PAC showed 77~84%, 70~83%, 53~60%, 27~36%, and 59~75%, respectively. The filtration time was determined to be around 10 to 20 minutes. Back-washing for 10 seconds by pressurized air resulted in a satisfactory regeneration efficiency. According to the aforementioned test results, the cylinder-shaped filter is effective in reducing turbidity and would be suitable for practical application in construction sites and farms.

• Membrane and Water Treatment
• /
• v.7 no.1
• /
• pp.11-22
• /
• 2016

The characterization of treatment performance with respect to mixed liquor suspended solids (MLSS) concentration enables greater control over system performance and contaminant removal efficiency. Hybrid membrane bioreactors (HMBRs) have yet to be well characterized in this regard, particularly in the context of greywater treatment. The aim of this study, therefore, was to determine the optimal MLSS concentration for a decentralized HMBR greywater reclamation system under typical loading conditions. Treatment performance was measured at MLSS concentrations ranging from 1000 to 4000 mg/L. The treated effluent was characterized in terms of biochemical oxygen demand ($BOD_5$), chemical oxygen demand (COD), turbidity, ammonia ($NH_3$), total phosphorus (TP), total kjeldahl nitrogen (TKN), and total nitrogen (TN). An MLSS concentration ranging from 3000 to 4000 mg/L yielded optimal results, with $BOD_5$, COD, turbidity, $NH_3$, TP, TKN, and TN removals reaching 99.2%, 97.8%, 99.8%, 99.9%, 97.9%, 95.1%, and 44.8%, respectively. The corresponding food-to-microorganism ratio during these trials was approximately 0.23 to 0.28. Operation at an MLSS concentration of 1000 mg/L resulted in an irrecoverable loss of floc, and contaminant residuals exceeded typical guideline values for reuse in non-potable water applications. Therefore, it is suggested that operation at or below this threshold be avoided.

• Journal of Environmental Science International
• /
• v.32 no.5
• /
• pp.355-363
• /
• 2023

This study used a batch DAF (dissolved air flotation) jar tester to evaluate the algae removal efficiency of alum and PAC coagulants during coagulation, flocculation, and flotation. Optimal coagulant dosages were 0.06 ~ 0.15 mL/L (12.0 ~ 26.0 mg Al/L,17%), 0.08 ~ 0.20 mL/L (10.0 ~ 24.0 mg Al/L, 12%), 0.25 ~ 0.30 mL/L (25.0 ~ 30.0 mg Al/L, 10%) for PAC, and 3.0 ~ 5.0 mL/L (81.0 ~ 135.0 mg Al/L, 2.7%) for alum. Turbidity of treated water was 1.0 ~ 2.0 NTU in optimal coagulation, flocculation, and flotation conditions for the four coagulants types. The amount of coagulant injected tended to decrease with increasing Al content in the coagulant, as follows : 17% PAC < 12% PAC < 10% PAC < 2.7% alum. Turbidity removal efficiencies were in the order of 12% PAC (93.6%) > 10% PAC (92.7%) > 17% PAC (91.3%) > 2.7% Alum (88.1%).

• Journal of environmental and Sanitary engineering
• /
• v.20 no.3 s.57
• /
• pp.36-43
• /
• 2005

Prior to the study of the sewage treatment methods, water quality for Gwangju sewage of fluent was investigated from January to December, 2004 for sewage water reuse. Monthly mean values of BOD, SS, turbidity, total phosphorus and color were 4.1 mg/L, 2.9 mg/L, 0.8 NTU, 1.3 mg/L, and 27 unit, respectively. Jar-test was performed to investigate the removal efficiency of pollutants under the coagulation conditions of fast mixing for 5 min, slow mixing for 15 min and precipitation for 1hr. Here, alum and polyaluminium chloride (PAC) were used as coagulants to reduce color, turbidity, total phosphorus (TP) and total organic carbon (TOC) in sewage effluents. The results showed that PAC gave better efficiency in removing turbidity and dissolved phosphorus than alum. It was also found from the relative molecular weight (RMW) distribution analysis that organic matter over 1,000 Dalton (Da) was easily removed by coagulation and subsequently MF treatment, while it was not effective for less than 500 Da. Based on tis result, Natural organic matter (NOM) with lower molecular weight (< 500 Da) may cause harmful disinfectant by-product (DBP) after chlorine treatment. Thus, activated carbon adsorption seems to be required for the complete removal of DBP in the hybrid system.

• Journal of Advanced Marine Engineering and Technology
• /
• v.38 no.3
• /
• pp.269-275
• /
• 2014

The objective of this study was to investigate the performance characteristics of an inline mixing and coagulation system for water treatment based on the process intensification concept. Three-stage inline mixing and coagulation system was composed of the reservoirs of source wastewater, the fixed quantity injection pumps of coagulants, the mixing and coagulation tubes, a sedimentation tank and a control panel. In the equal dosage of coagulant and coagulant aids, the turbidity removal with increasing the dosage of coagulant aids was about 3 times higher than that with increasing the dosage of coagulant. In the condition of the equal mixing and coagulation time, the turbidity removal of inline mixing and coagulation system was about 4.6 times higher than that of mechanical type.

• The Journal of Engineering Geology
• /
• v.16 no.2 s.48
• /
• pp.153-159
• /
• 2006

The discharges of time, technology and finance was increased and it was difficult to use water resources effectively by serious water pollutions. Thus the main aim of this work was focused on effectiveness of water treatment process using non-controlled indicators such as UV absorbance($E_{260}$) and particle counts that provided analytical results with simple and rapid. The soluble aluminum was increased by the increase of aluminum doses for turbidity removals It means that the water quality was not controlled by only turbidity monitoring cause maximum turbidity removal did not guarantee minimum residual aluminum in an aluminum-based coagulation. E removal efficiency appeared to be the promising indicator for monitoring the effectiveness of the water quality process such as coagulation and nanofiltration membranes for arsenic(V). On the basis of the particle monitoring, it was also found that the particle counts could be used very useful for changing the coagulants in real water treatments.

• Journal of Environmental Health Sciences
• /
• v.29 no.1
• /
• pp.74-83
• /
• 2003

Microcystin, stable compounds with circular heptapeptides, is presented inside cyanobacterial cell. So far, over 30 types have been known to exist and microcystin-LR, RR among them are the most potent toxin compound. By this reason, a strong oxidant, ozone was used in this study to remove the microcystins produced by cyanobacteria. Removal efficiency of microcystin at M water treatment plant was also evaluated. Microcystin concentration was determined by protein phosphatase inhibition assay. The results showed that dissolved microcystin in raw water detected in the range of 0.011-0.028 ㎍ Microcystin-RR equivalent/l. Above 98% of microcystin was removed through overall treatment system. Therefore, the water treatability of M treatment plant seemed to be excellent. Removal efficiency of microcystin according to unit process varied as characteristics of raw water such as DOC, UV/sub 254/ and turbidity. Removal efficiency of microcystin by ozonation was investigated in laboratory according to contact time and ozone dose. Dissolved microcystin was increased by twice fold according to ozone contact time, but increased by fifth fold according to ozone dose. So, changing of ozone dose more affected microcystin release than changing of ozone contact time. Behavior of microcystin by ozonation was similar to that of DOC, and residual ozone concentration gave influence to removal ratio of microcystin. In conclusion, single ozone treatment wasn't effective on microcystin removal in case of water containing a lot of cells. Therefore, it's more effective to use ozonation process after the removal of cyanobacterial cells in advance.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.37 no.1
• /
• pp.18-23
• /
• 2004

Effect of initial protein concentration on the protein removal rate was assessed for seawater aquarium using a foam separator. Protein removal rate was increased and removal efficiency was decreased with the increase of initial protein concentration. Enrichment ratio was decreased and foam generation rate was increased with the increase of initial protein concentration. Total suspended solids (TSS) removal rate was increased with the increase of initial protein concentration, and TSS removal efficiency was decreased with the increase of initial protein concentration. Turbidity removal rate and removal efficiency were increased with the increase of initial protein concentration.

• Journal of Environmental Health Sciences
• /
• v.27 no.2
• /
• pp.60-66
• /
• 2001

Natural organic matters(NOMs) are found everywhere such as soil, surface and ground waters and consist of both humic and nonhumic components, and their heterogeneith makes each source unique. This study was carried to evaluate the removal characteristics of NOMs by mixing coagulants and the variation of apparent molecular weight distribution(AMWD) in coagulation process. Ratio of optimum coagulants dosage for removal of DOC and turbidity by mixing coagulants was 1.83 mM F $e^{3+}$/mM $Al^{3+}$. DOC removal increased at lower pH. The pH6 control focused on the removal of organic matters could reduce the amount of coagulant consumption by 2 to 3 times based on the pH8.5 of natural water. The dissolved organic matters in the natural water from the mid-stream of Han River were composed of the low molecular weight(LMW,<1 K) of 59.7%, and the medium and high molecular weight(M.HMW, 1~30 K) of 40.3%, respectively. At pH6, the DOC removal efficiencies of LMW(<1 K) and M.HMW(1~30 K) in coagulation process were 27~35%, 62~72%, respectively. The fraction smaller than 1 K was not eliminated to a noticeable degree, while the fraction of 1~30 K was relatively well removed. In conclustion, mixing coagulants were fairly effective in the removal of natural organic matter.r.