Water treatment processes, dissolved organic matter

Win YY, Kumke MU, Specht CH, Schinde-LiN AJ, Kolliopoulos G, Ohlenbusch G, Kleiser G, Hesse S, Erimmel EH (2000) Influence of Dissolved Organic Matter (DOM) on Subsequent Water Treatment Processes, Wat. Res. 34, No. 7 2098-2104. 

Since aluminum oxide is amphoteric, alum could theoretically be recovered from the WTR under alkaline conditions as well. Figure 34.1 shows both dissolved organic carbon (DOC) and Al(III) concentration in Allentown, Pennsylvania under water treatment plant conditions. Since a high concentration of dissolved organic matter is very undesirable in recovered alum due to its THMFP, even the alkali digestion process is unable to achieve selective alum recovery. 

Eor water-treatment processes such as drinking water or potable water production, reverse osmosis (desalination), nanofiltration, and ultrafiltration are mainly used. In these processes often a microfiltration stage is implemented as the first cleaning stage for the removal of dissolved organic matter, colloids and particles from the source. 

Hydrophilic acids represent about 30% of NOM and are sometimes called " hydrophilic HSs This part of NOM is the least characterised and is more difficult to isolate and purify. Volatile fatty acids or sugar acids could be part of this component (Thurman (1983)). To study the impact of these hydrophilic HSs on water treatment processes, both complete NOM samples and fractions such as HS need to be considered. It is therefore important not to concentrate on HSs only, but also compare to NOM. Organic matter also occurs in natural waters as dissolved molecules, as suspended sediments in the form of coated particles and on coated bottom sediments (Thurman (1983)). This colloid-organic interaction will be addressed specifically in a later section (2.9). 

Membranes are used for the treatment of contaminated aqueous solutions to produce water with a specific quality for different uses, including potable water and distilled water. Among the membrane processes, nanofiltration (NF) has been increasingly used for the treatment of wastewaters, such as natural organic matter (NOM) aqueous solutions. Humic acid (HA) is one of the common NOM that causes a major problem in surface water purification. HA is classified as a dissolved organic carbon (DOC) and has an impact on water color for concentrations above 5 mg/1 (Schafer et al. 2000). 

It is not always possible to get good quahty water for the industry from the local sources. The raw water may contain salts of calcium, magnesium, sodium etc. These can canse both temporary as well as permanent hardness. It may also contain floating imprrrities, dissolved solids, organic impurities like chlorides, sulphates, dissolved oxygen etc. This water needs to be treated before it can be used in the process or for cooling dnties etc. Otherwise it can spoil the final product quality due to insoluble matter, cause corrosion of equipment, waste the fuel due to formation of scales in boilers, npset process conditions due to scales in the cooling jackets and so on. Hence, it is essential to procure a water treatment plant or create the facility in-house. 

Biology. The major biological treatment processes used in waste-water treatment are biological oxidation of dissolved and fine suspended organic matter in wastewater (secondary treatment) and stabilization... 

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