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Abstract

The recent climate condition and pollution problem related to surface water have led to water scarcity in Malaysia. Huge amount of groundwater has been identified as viable source for drinking water. This paper was aimed to investigate groundwater’s quality at specific location and metakaolin’s potential in the groundwater treatment in the removal of manganese. Groundwater purging was determined to be sufficient at 120 minutes where all three parameters (pH, dissolved oxygen and conductivity) were stabilized. The groundwater studied is classified as both anoxic and reductive due the low dissolved oxygen value. It also can be categorized as brackish due to high value of conductivity and total dissolved solid. Manganese content in groundwater was determined as higher than of that permissible limit for raw water and drinking water which makes it unsuitable for them not suitable for consumption and cleaning purpose. Average manganese concentration in samples was 444.0 ppb where the concentrations of manganese ranged from 229.4 ppb to 760.3 ppb. Manganese developed is not that a strong positive correlation against iron concentration, total dissolved solids and conductivity; whereas has a moderate negative correlation against dissolved oxygen. The capability adsorption of manganese by metakaolin was assessed via batch method which indicated optimum dosage and contact time was 14g that removed average 30.2% and contact time optimum at 120 minutes which removed 33.2% manganese from the sample.

Abstract

Coagulation process is widely used for removal of natural organic matters (NOM) and for water color intensity reduction. The efficiency of coagulation process depends on many different factors. Aim of this research is to investigate coagulation process under different conditions. During the research coagulation process was held at different pH values (5.5; 6.0; 6.5), at different water alkalinity and at different water turbidity. It was found that removal of NOM and water color intensity reduction is most effective at pH values from 5.5 to 6.0. At these conditions water color intensity reduction is most efficient, but removal of dissolved organic carbon (DOC) is the lowest. During the research it was also found that different water alkalinity and turbidity do not make significant influence on efficiency of coagulation process.

Abstract

One of the problems with iron removal from groundwater is organic matter. The article presents the experiments involved groundwater samples with a high concentration of total iron - amounting to 7.20 mgFe/dm3 and an increased amount of organic substances (TOC from 5.50 to 7.50 mgC/dm3). The water samples examined differed in terms of the value of the ratio of the TOC concentration and the concentration of total iron (D). It was concluded that with increase in the coexistence ratio of organic substances and total iron in water (D = [TOC]/[Fetot]), efficiency of Fe(II) to Fe(III) oxidization with dissolved oxygen decreased, while the oxidation time was increasing. This rule was not demonstrated for potassium manganate (VII) when used as an oxidizing agent. The application of potassium manganate (VII) for oxidation of Fe(II) ions produced the better results in terms of total iron concentration reduction in the sedimentation process than the oxidation with dissolved oxygen.

Abstract

The article discusses effectiveness of treatment of groundwater with increased natural organic matter content with the use of organic polyelectrolytes. The effects of water treatments were determined by the ionic character of the polyelectrolyte and its dose. Due to the amount of removed general ferric and coloured matters a greater usefulness of anionic and non-ionic polyelectrolytes was shown, while due to decreased turbidity and TOC, cationic flocculants proved more useful. Using the Praestol 2540 semi-anionic polyelectrolyte as the substance aiding the coagulation process decreased the effectiveness of groundwater treatment, especially in terms of the removal of iron and organic substances when using the PIX-112 coagulating agent.

Abstract

Fluoride removal from aqueous solutions was studied using nanofiltration and sorption techniques which have always been best key ways to deal with water contaminated by fluoride. In this presented work, we were firstly interested on fluoridated rejected water overcoming the drawback of RO membrane process of groundwater treatment plant in Baltic region (Kretinga, Lithuania). Opoka sorbent has shown effective results of fluoride sorption with efficiency higher than 77 %. In order to understand the sorption phenomenon and to validate the results obtained, we have applied experimental data on Freundlich and Langmuir isotherms which allow us to determine isotherms parameters (KF; 1/n and KL; q max) and to confirm the experiment. Because of the unacceptable tariff of drinking water treated by RO, defluoridation with nanofiltration method is proposed in this study as a solution which can replace reverse osmosis technique. For that, tests of nanofiltration for fluoride removal were carried out at laboratory scale by using nanofiltration flat sheet membranes (NF270 and NF90).

Abstract

The article presents research results of the introduction of powdery activated carbon to the existing technological system of the groundwater treatment stations in a laboratory, pilot plant and technical scale. The aim of the research was to reduce the content of organic compounds found in the treated water, which create toxic organic chlorine compounds (THM) after disinfection with chlorine. Nine types of powdery active carbons were tested in laboratory scale. The top two were selected for further study. Pilot plant scale research was carried out for the filter model using CWZ-30 and Norit Sa Super carbon. Reduction of the organic matter in relation to the existing content in the treated water reached about 30%. Research in technical scale using CWZ-30 carbon showed a lesser efficiency with respect to laboratory and pilot-plant scale studies. The organic matter decreased by 15%. Since filtration is the last process before the individual disinfection, an alternative solution is proposed, i.e. the second stage of filtration with a granular activated carbon bed, operating in combined sorption and biodegradation processes. The results of tests carried out in pilot scale were fully satisfactory with the effectiveness of 70–100%.

membrane RO, J. Membrane Sci . 289, 123-137. Doi:10.1016/j.memsci.2006.11.043. 7. Gabelich, C.J., Williams, M.D., Rahardianto, A., Franklin, J.C. & Cohen, Y. (2007). High-recovery reverse osmosis desalination using intermediate chemical demineralization, J. Membrane Sci . 301, 131-141. Doi:10.1016/j.memsci.2007.06.007. 8. El-Manharawya, S. & Hafezb, A., (2002). Study of seawater alkalization as a promising RO pretreatment Method. Desalination , 153, 109-120. 9. Al-Rehaili, A.M. & Alabdula’aly, A.I. (1999). Chemical and economical evaluation of groundwater treatment

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