• 상하수도학회지
• /
• 제24권5호
• /
• pp.581-593
• /
• 2010

The objectives of this study were to investigate the effects of raw water pH and basicity of coagulants on turbidity removal with several raw waters having different level of turbidity, alkalinity and pH. Raw waters were sampled from M, S and B water treatment plants(WTP) located at Miryang, Nakdong, Han river, respectively. Six coagulants which have different levels of basicity and aluminum contents were used for this evaluation. High basicity of the coagulant helped to properly control coagulation processes for treating turbid and low alkali raw water. It was difficult for operators to determine optimum coagulant dose for high basicity coagulants, since residual turbidity tended to decrease continuously as coagulant dose increased. Turbidity removal efficiencies with high basicity coagulants(E and F) were higher than the other coagulants at ambient pH for the M WTP. Turbidity removal efficiencies, however, at adjusted pH 7.0 showed similar among six coagulants. Residual turbidity kept low at excess dosages with high basicity coagulants. Optimum coagulant dosages at adjusted pH 7.0 showed higher than those at ambient pH in M WTP. On the contrary in B WTP, optimum coagulant dosage at ambient pH were higher than that at adjusted pH 7.0.

• 상하수도학회지
• /
• 제23권1호
• /
• pp.39-46
• /
• 2009

A method to improve water treatment efficiency by coagulant overdosing for high pH raw water at a drinking water treatment plant (WTP) which had no pH adjusting facilities was investigated. Poly aluminum chloride (PACl) was used for coagulant, and turbidity removal efficiency was evaluated as a function of PACl dosage increases. pH and turbidity of supernatant of jar-tester were 7.10 and 0.50 NTU respectively, when the turbidity, pH, alkalinity, water temperature, conductivity of raw water were 1.75 NTU, 9.38, 46.5 mg/L, $6.4^{\circ}C$, $400{\mu}s/cm$, respectively. Turbidity of settled water was reduced from 2.18 NTU to 0.28 NTU (87% reduction) when PACl dosage was increased from 16 mg/L to 45 mg/L at a full scale WTP. This can be attributed to the recovery of coagulant efficiency by pH reduction with the increase of coagulant dose, however coagulation efficiency was reduced with the formation of Al(OH)4- by PACl addition at higher pH. Coagulant overdosing was proven to be a rapid and effective method for high pH raw water, which can be applied at drinking WTP.

• 한국미생물·생명공학회지
• /
• 제26권3호
• /
• pp.257-263
• /
• 1998

Alcaligenes eutrophus의 세포배양액(23-210 g dry weight/L)으로부터 균체 회수 효율에 미치는 철계 응집제 첨가 효과에 대해 연구하였다. 응집제로는 무기 응집제인 Fe$_2$(SO$_4$)$_3$과 무기 고분자 응집제인 Ferix-3를 사용하였다. 철계 응집제는 3-13의 넓은 pH 범위에서 응집효과를 나타내었으며, 배양액의 pH가 증가할수록 floc의 크기는 증가하였다. 균체 회수를 위한 배양액의 최적 pH는 10-13이었다. 최적 응집제의 첨가량은 세포농도가 증가함에 따라 증가하였는데, 무기응집제인 Fe$_2$(SO$_4$)$_3$보다는 무기고분자응집제인 Ferix-3이 적은 농도에서 응집 효율이 우수함을 알 수 있었다. 210 g/L의 세포농도 배양액에 Ferix-3을 1300 mg Fe/L를 첨가하면 45$\times$g의 낮은 원심력에 의해 95%이상의 균체를 회수 가능하였다. 응집제의 요구량은 배양액 중의 NH$_4$$^{+}$ 농도에 비례하여 증가하였고, 배양액 중의 NH$_4$$^{+}$ 농도가 1 g 증가하면 응집제가 0.066 g Fe$_3$$^{+}$정도 더 요구되었다.

• 청정기술
• /
• 제15권1호
• /
• pp.38-41
• /
• 2009

적니(red mud)는 보오크싸이트로부터 수산화알루미늄/알루미나를 제조하는 Bayer 공정에서 부산물로 발생되는 폐기물이다. 본 연구에서는 적니로부터 철과 알루미늄을 염산으로 침출시켜 폐수처리용 응집제를 제조하였다. 적니응집제를 합성폐수에 투입한 후 조절된 pH가 증가함에 따라 중금속이온 제거율이 증가하였다. 적니응집제 제조 시에 적니의 양이 증가할수록 Fe의 침출효율은 낮아졌으나, 적니응집제의 pH는 적니의 양이 증가할수록 높아졌다. 적니응집제와 물을 혼합한 용액을 다시 적니와 반응시켜 Fe 및 Al의 농도가 더 증가되고, pH가 향상된 침출액을 얻었다. 이 침출액의 pH는 다른 응집제 $FeCl_3$와 $Fe_2(SO_4)_3$의 pH와 비슷한 값을 보였다.

• 대한환경공학회지
• /
• 제38권4호
• /
• pp.169-176
• /
• 2016

수처리용 응집제로서 미리 가수분해시켜 고분자성 Fe(III)의 이용과 제조에 대한 연구에서, Ferron 분석법을 통해 Fe(III) 응집제내에 함유된 가수분해종을 정량화하고 그 차이를 살펴보았다. 제조된 PICl (polymeric iron chloride) 중에서 r = 1.5의 경우에서 가장 많은 20%의 고분자성 Fe(III)종을 함유하고 있는 것으로 나타났다. 응집 실험은 r 값에 따라 제조된 응집제를 이용하여 응집제 주입량과 응집 pH의 조건을 달리하여 수행하였다. $FeCl_3$ (r = 0.0)와 PICl (r = 0.5, 1.0, 1.5)를 이용한 응집 특성 비교에서, PICl (r = 0.5, 1.0, 1.5)에서 $FeCl_3$ (r = 0.0) 보다 유기물 제거에 효과적인 것으로 나타났다. 응집 pH에 따른 응집 실험에서도 PICl의 경우에서 pH에 대한 영향이 적게 나타났으며, 폭 넓은 응집 pH(pH 4-9)에서 탁도와 유기물 제거효율이 높은 것으로 나타났다.

• 한국염색가공학회지
• /
• 제14권2호
• /
• pp.40-50
• /
• 2002

In order to remove the pollutants effectively in the dye wastewater by chemical precipitation process, coagulation arid flocculation test were carried out using several coagulants on various reaction conditions. It was found that the Ferrous sulfate was the most effective coagulant for the removal of disperse dye(B79), and we could get the best result lot the removal of disperse dye(B56) in the aspects of TOC removal efficiency and sludge field. When the Ferrous sulfate dosage was $800mg/\ell$, the sludge settling velocity was very fast>, and the color was effectively removed in the disperse dye(B79) solution. Although the color removal was ineffective when the Alum was used as a coagulant, the sludge field was decreased in comparison with the Ferrous sulfate or the Ferric sulfate was used in the disperse dye(B56) solution. The general color removal effect for the disperse dye(B56 and B79) solutions, the Ferric sulfate was more proper coagulant than the Alum. It was showed that TOC removal was improved 5% and over by the addition of Calcium hydroxide, and $30mg/\ell$ of sludge yield was decreased(B79). When Alum or Ferric sulfate was used as a coagulant, pH condition for most effective color removal was 5 in B56 solution. In case of Ferrous sulfate as a coagulant, most effective pH condition for color removal was 9. When Ferric sulfate or Ferrous sulfate was used as a coagulant, pH condition for most effective color removal was 9 in B79 solution.

• 상하수도학회지
• /
• 제28권5호
• /
• pp.601-608
• /
• 2014

A coagulation-flocculation (CF) process using aluminum sulfate as a coagulant was employed to treat highly suspended solids in tunnel wastewater. Response surface methodology (RSM) based on a Box-Behnken design was applied to evaluate the effects of three factors (coagulant dosage, pH and temperature) on total suspended solids (TSS) removal efficiency as well as to identify optimal values of those factors to maximize removal of TSS. Optimal conditions of coagulant dosage and pH for maximum TSS removal changed depending on the temperature ($4{\sim}24^{\circ}C$). As temperature increased, the amount of coagulant dosage and pH level decreased for maximum TSS removal efficiency during the CF process. Proper adjustment of optimal pH and coagulant dosage to accommodate temperature fluctuations can improve TSS removal performance of the CF process.

• Ocean Science Journal
• /
• 제41권4호
• /
• pp.221-226
• /
• 2006

More attention has been paid to the research on decolorization of dyeing wastewater nowadays. In this study, an investigation into the decolorization of dyeing wastewater was conducted using a combination of coagulant, carboxymethyl chitosan (NOCC) and coagulant aid, polyscrylamide (PAM). The factors influencing the decolorization efficiency, such as pH value, coagulant and the dosages of coagulant, were discussed. The results showed that using PAM as coagulant aid could reach a high decolorization efficiency compared with using NOCC alone. The optimal conditions were pH 2.3, 480 mg/L for NOCC, and 4-8 mg/L for PAM. Under the optimum conditions, the rate of decolorization could achieve 99%, and the removal of chemical oxygen demand (COD) could achieve 90%. In addition, the membrane processes with chitosan/rare-earth-metals could enhance the decolorization rate of Direct Black FF to 94.7%, and Indanthren Red F3B to 98.2%, respectively.

• Environmental Engineering Research
• /
• 제11권1호
• /
• pp.45-53
• /
• 2006

Conventional coagulation is still the main treatment process for algae removal in water treatment. The coagulation efficiency can be significantly improved by the preoxidation of algae-containing water. Jar test was conducted to determine the optimal condition for the removal of diatoms, especially Cyclotella sp. by preoxidation and the subsequent coagulation. The effects of various concentration of PAC (Polyaluminum chloride) on coagulation with and without preoxidation using chlorine or potassium permanganate at different pHs (7.7 and 9.0) were evaluated. At pH 7.7, preoxidation with 2ppm $Cl_2$ followed by coagulation with 7.5 ppm PAC coagulant could reduce Cyclotella sp. concentration by 86%. At pH 9.0, preoxidation with 1 mg $KMnO_4/L$ followed by coagulation with 12.5 ppm PAC coagulant reduced Cyclotella sp. concentration by 85%. Non-linear regression was applied to determine the optimal condition. At pH 7.7 and 9.0, R was over 0.9, respectively. The pH of algal blooming water is over 9.0. Algae (diatom; Cyelotella sp.) can be controlled in the following ways: preoxidation with 1 mg $KMnO_4/L$ followed by coagulation with 12.5 ppm PAC coagulant can remove 80% algae from water. If water pH is adjusted to 7.7, it was expected that less amount of coagulant (7.5 or 10 mg PAC /L) after preoxidation ($Cl_2$ 2 ppm or $KMnO_4$ 0.33, 1 ppm) would be needed to achieve similar level of algae removal. The oxidation with 0.33ppm $KMnO_4$ followed by coagulation with 7.5 ppm PAC coagulant was preferable due to cost-effectiveness of treatment condition and color problem after treatment.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
• /
• pp.317-320
• /
• 1997

In the water purification plant, chemicals are injected for quick purification of raw water. It is clear that the amount of chemicals intrinsically depends on the water quality such as turbidity, temperature, pH and alkalinity etc. However, the process of chemical reaction to improve water quality by the chemicals is not yet fully clarified nor quantified. The feedback signal in the process of coagulant dosage, which should be measured (through the sensor of the plant) to compute the appropriate amount of chemicals, is also not available. Most traditional methods focus on judging the conditions of purifying reaction and determine the amounts of chemicals through manual operation of field experts or jar-test results. This paper presents the method of deriving the optimum dosing rate of coagulant, PAC(Polymerized Aluminium Chloride) for coagulant dosing process in water purification system. A neural network model is developed for coagulant dosing and purifying process. The optimum coagulant dosing rate can be derived the neural network model. Conventionally, four input variables (turbidity, temperature, pH, alkalinity of raw water) are known to be related to the process, while considering the relationships to the reaction of coagulation and flocculation. Also, the turbidity in flocculator is regarded as a new input variable. And the genetic algorithm is utilized to identify the neural network structure. The ability of the proposed scheme validated through the field test is proved to be of considerable practical value.