Suraphong Wattanachira

Reduction of DOM fractions and their trihalomethane formation potential in surface river water by in-line coagulation with ceramic membrane filtration.

This research was aimed at investigating the reduction of DOM fractions and their trihalomethane formation potential (THMFP) by in-line coagulation with 0.1 μm ceramic membrane filtration. The combination of ceramic membrane filtration with a coagulation process is an alternative technology which can be applied to enhance conventional coagulation processes in the field of water treatment and drinking water production. The Ping River water (high turbidity water) was selected as the raw surface water because it is currently the main raw water source for water supply production in the urban and rural areas of Chiang Mai Province. From the investigation, the results showed that the highest percent reductions of DOC, UV-254, and THMFP (47.6%, 71.0%, and 67.4%, respectively) were achieved from in-line coagulation with ceramic membrane filtration at polyaluminum chloride dosage 40 mg/L. Resin adsorption techniques were employed to characterize the DOM in raw surface water and filtered water. The results showed that the use of a ceramic membrane with in-line coagulation was able to most efficiently reduce the hydrophobic fraction (HPOA) (68.5%), which was then followed by the hydrophilic fraction (HPIA) (49.3%). The greater mass DOC reduction of these two fractions provided the highest THMFP reductions (55.1% and 37.2%, respectively). Furthermore, the in-line coagulation with ceramic membrane filtration was able to reduce the hydrophobic (HPOB) fraction which is characterized by high reactivity toward THM formation. The percent reduction of mass DOC and THMFP of HPOB by in-line coagulation with ceramic membrane filtration was 45.9% and 48.0%, respectively.

Interaction Between Organic Species in the Formation of Haloacetic Acids Following Disinfection

The formation of haloacetic acids (HAAs) from the chlorination of individual and binary mixtures of organic fractions obtained from the intake of Bangkhen Water Treatment Plant in Bangkok, Thailand was investigated. Experimental results revealed that, as an individual fraction, hydrophobic base (HPOB) was the most active in forming HAAs (approx. 200 microg/mg) whereas hydrophilic acid (HPIA) was the least (approx. 40 microg/mg). In binary mixtures, acid fractions exhibited stronger inhibitory effect in forming HAAs than base fractions. With the set of experimental data obtained from this work, no relationships between specific HAA formation potential and various organic fractions concentrations in binary mixtures could be formulated. Among the various individual HAA species obtained from the chlorination of each individual organic fraction, dichloroacetic acid (DCAA) was found to be predominant. On the other hand, the chlorination of binary organic fraction mixtures often led to the formation of monochloroacetic acid (MCAA) as the predominant HAA species.

Kinetics of trihalomethane formation from organic contaminants in raw water from the bangkhen water treatment plant

The fractionation of raw water from Bangkhen water treatment plant, Bangkok, Thailand revealed that the mass distribution sequence of the six organic fractions from high to low was hydrophilic neutral (HPIN), hydrophobic acid (HPOA), hydrophilic acid, hydrophobic neutral, hydrophilic base, and hydrophobic base. The main organic matter components in raw water were HPIN and HPOA, which were also the two most important contributors of trihalomethane formation potential (THMFP). Linear dependencies between the level of each organic fraction and the formation potential of THM species were observed, which suggested the reactions between the organic fraction and chlorine during the chlorination were first order. The fractionation led to a deviation of bromide concentration in each organic fraction from the original concentration, and this affected the formation of brominated THM species. However, this effect was demonstrated to be within an acceptable range. The chlorination of an individual organic fraction resulted in a higher level of THMFP than that of the raw water and mixed fractions, indicating an inhibitory effect between the organic species. *Presented at “The 2nd Asian International Conference on Ecotoxicology and Environmental Safety” (SECOTOX 2004), Songkla, Thailand, 26–29 September 2004.

Identification of dissolved organic matter in raw water supply from reservoirs and canals as precursors to trihalomethanes formation

The characteristic and quantity of dissolved organic matter (DOM) as trihalomethanes precursors in water from the U-Tapao Basin, Songkhla, Thailand was investigated. The sources of water in the basin consisted of two reservoirs and the U-Tapao canal. The canal receives water discharge from reservoirs, treated and untreated wastewater from agricultural processes, communities and industries. Water downstream of the canal is utilized as a raw water supply. Water samples were collected from two reservoirs, upstream and midstream of the canal, and the raw water supply in the rainy season and summer. The DOM level in the canal water was higher than that of the reservoir water. The highest trihalomethane formation potential (THMFP) was formed in the raw water supply. Fourier-transform infrared peaks of the humic acid were detected in the reservoir and canal waters. Aliphatic hydrocarbon and organic nitrogen were the major chemical classes in the reservoir and canal water characterized by a pyrolysis gas chromatography mass spectrometer. The optimal condition of the poly aluminum chloride (PACl) coagulation was obtained at a dosage of 40 mg/L at pH 7. This condition could reduce the average UV-254 to 57%, DOC to 64%, and THMFP to 42%. In the coagulated water, peaks of O-H groups or H-bonded NH, C˭O of cyclic and acyclic compounds, ketones and quinines, aromatic C˭C, C-O of alcohols, ethers, and carbohydrates, deformation of COOH, and carboxylic acid salts were detected. The aliphatic hydrocarbon, organic nitrogen and aldehydes and ketones were the major chemical classes. These DOM could be considered as the prominent DOM for the water supply plant that utilized PACl as a coagulant.

A concept for planning and management of on-site and centralised municipal wastewater treatment systems, a case study in Bangkok, Thailand. I: Pollutant discharge indicators and pollutant removal efficiency functions

The concept of pollution load indicators for planning and management of the mixture conditions of centralised and on-site wastewater treatment systems has not been discussed in detail so far. In this paper, pollutant discharge (load) indicators and pollutant removal efficiencies were quantitatively analysed to develop a part of a strategy for planning and management of municipal wastewater treatment systems (WWTSs) under the mixture conditions in Bangkok, Thailand, as a case study. Pollutant discharge indicators of on-site WWTSs were estimated based on the relevant literature. Three kinds of pollutant removal efficiency function at centralised wastewater treatment plants (CWWTPs) were empirically developed for biological oxygen demand, chemical oxygen demand, total nitrogen, total phosphorus, total coliforms and faecal coliforms based on the existing CWWTP management data. These results will be integrated into the scenario-based analysis in the second paper in the series. The results will be base datasets, and the concept and estimation methods can be applied for wastewater treatment planning and management in other areas.

A concept for planning and management of on-site and centralised municipal wastewater treatment systems, a case study in Bangkok, Thailand. II: Scenario-based pollutant load analysis

Scenario-based pollutant load analysis was conducted to develop a part of a concept for planning and management of wastewater treatment systems (WWTSs) under the mixture conditions of centralised and on-site WWTSs. Pollutant discharge indicators and pollutant removal efficiency functions were applied from another paper in the series, which were developed based on the existing conditions in urban and peri-urban areas of Bangkok, Thailand. Two scenarios were developed to describe development directions of the mixture conditions. Scenario 1 involves keeping the on-site wastewater treatment plants (WWTPs) within the areas of centralised WWTSs. Scenario 2 is dividing the centralised and on-site WWTS areas. Comparison of the smallest values of total pollutant discharge per capita (PDCtotal) between Scenarios 1 and 2 showed that the smallest PDCtotal in Scenario 1 was smaller than that in Scenario 2 for biological oxygen demand, chemical oxygen demand and total phosphorus whereas the smallest PDCtotal in Scenario 2 was smaller than that in Scenario 1 for total nitrogen, total coliforms and faecal coliforms. The results suggest that the mixture conditions could be a possible reason for smaller pollutant concentrations at centralised WWTPs. Quantitative scenario-based estimation of PDCtotal is useful and a prerequisite in planning and management of WWTSs.

A novel plate settler in immersed membrane bioreactor (iMBR) in reducing membrane fouling

AbstractMembrane separation technology has been widely applied in water and wastewater treatments, especially in the water reclamation and recycling. However, the membrane fouling decreases the membrane efficiency and increases the cost of the process, thus limiting the membrane application. There are two types of membrane bioreactors (MBRs), immersed (iMBR) and side streamed. However, the membrane surfaces of these two types of MBR are always directly exposed to high concentration of suspended solids (SS) and easily get fouling. A novel MBR was designed to reduce membrane fouling. Incorporation of inclined plate in MBR can separate high SS from direct contact with the membrane surface and decreases membrane fouling. The iMBR used in this study consists of an aeration zone, a settling zone, and a filtration zone. The reactor operated under the upflow mode of operation with 0.06 μm membrane pore size and with and without membrane backwashing. The results showed that the novel iMBR can reduce the SS concent...

Child-education program for the reduction of health risks due to fluoride in water sources in the Chiang Mai Basin, Thailand

Groundwater is the major source of drinking water in Lamphun Province in the Chiang Mai Basin, Thailand. However, groundwater contains high fluoride up to 16 mg F/L, which has caused dental and skeletal fluorosis. Although Thai Government installed RO membrane plants for the removal of fluoride from groundwater; and delivers RO-filtered bottled water that contains less fluoride than the Thai Standard of 0.7 mg F/L, it was found that the urinary fluoride levels are still high among the residents. To find the major sources of fluoride intake, fluoride contents in various water sources, such as village water supply, shallow and deep groundwaters, rain water and bottled water, were measured, and the local peoples behavior on water uses was recorded by interview and questionnaire study. As a result, it was found that the highest risk of fluoride ingestion comes from cooking rice with fluoride-containing water because of a lack of knowledge on fluoride sources and fluoride chemistry. To reduce the health risks arising from fluoride intake, a hands-on educational program on the sources and risks of fluoride in water was developed and implemented in the local schools. The participatory educational program promoted active involvement of schoolchildren, but it was found that the effectiveness of education varied depending on the questions we asked. Therefore, it needs to be improved by an iterative and interactive educational program. In conclusion, it was found that the benefits of providing safe drinking water using such advanced technology as RO membrane can be maximized only when it comes along with a participatory educational program on fluoride sources and health risks.

Bacteriophage Removal Efficiency of In-line Coagulation with Ceramic Membrane Filtration

The main objectives of this study are to evaluate the removal efficiency of bacteriophage Qβ using in-line coagulation with ceramic membrane filtration at different coagulant dosages, ceramic membrane pore sizes and initial bacteriophage Qβ concentrations. Raw water was collected from the Ping River, Chiang Mai, Thailand, and spiked with bacteriophage Qβ to prepare an initial concentration of 8x106 PFU/ml. According to the resulted, it was found that the smaller pore sizes membrane yield higher bacteriophage Qβ log removal. However, the use of a ceramic membrane alone could not remove bacteriophage Qβ completely. In-line coagulation combined with ceramic membrane filtration was conducted. The optimal polyaluminum chloride (PACl) doses for the 1.0, 0.5 and 0.1 μm pore size membranes were 2.5, 2.0 and 1.5 mg-Al/L, respectively. Bacteriophage Qβ removal at the optimal PACl dose was more than 6.7 log in all cases. The results of effect of different initial bacteriophage Qβ concentration on the removal efficiency showed that in-line coagulation with ceramic membrane at all pore sizes can completely remove bacteriophage Qβ when the initial concentration was low (5x105 PFU/ml). However, the higher initial bacteriophage Qβ concentrations (4x106 and 8x107 PFU/ml) required a higher PACl dose to obtain effective bacteriophage Qβ removal.