WASTEWATER TREATMENT PLANTWastewater Treatment Plant eliminates contaminants occurred from production process from factory or household. The treatment will completely eliminate or partially eliminate contamination to the level that meets water quality standard. The wastewater from different sources (for example, industrial, building, housing estate and agriculture) has different chemicals or contaminants, which can be divided into 5 categories as followings:
1. Wastewater with organic substances: from consumption, Biochemical Oxygen Demand (BOD) measures the condition of wastewater. BOD shows the amount of Oxygen required by bacteria to decompose organic substances. Wastewater with low BOD, when discharged into river or canal, will not have negative impact. On the other hand, wastewater with high BOD will cause lower Oxygen in the water and kill fishes or other living things in such resources.
2. Wastewater with chemical substances: Chemical Oxygen Demand (COD) measures the condition of wastewater. COD shows the amount of Oxygen used in oxidization process to obtain Carbon Dioxide (CO2) and water (H2O).
3. Wastewater with suspension: It has Total Dissolved Solid (TDS) at the level, which requires treatment. TDS value is the amount of dissolved solids, which flow through glass fiber filter. After filtering out suspension, liquid will be evaporated, leaving the solute.
4. Wastewater with heavy metals
5. Wastewater with other chemical substances
Wastewater treatment plant services depend on the categories of the wastewater and the level of treatment needed. The Company has two types of wastewater treatments as follows:
2.1 Wastewater Recycle Plant Wastewater Recycle Plant is wastewater treatment process for industrials and industrial estates to improve the quality of wastewater until it can be used again in the production process. Wastewater Recycle Plant improves quality of wastewater from production process which no cost for raw water, therefore, the costs of water reduce. Moreover, Wastewater Recycle Plant preserves environment and reduces water usage from water resources.
Wastewater Recycle Plant Process
- Flow Wastewater through membrane filtration system, MF or UF, to separate suspension.
- Flow Wastewater from membrane filtration system into RO to filter solute from wastewater and store in the storage for further usage.
2.2 Wastewater Treatment Plant Wastewater Treatment Plant is wastewater treatment process for industrials and communities to meet the standards for discharging into water resources.
The services can be divided into 3 categories based on type of wastewater as followings:
1. Physical and Chemical Treatment It is a preliminary treatment for wastewater from industrials and large communities by screening, grease and oil separation, chemical precipitation and heavy metal treatment.
2. Biological Treatment It used biological concept. The Company designs and builds a system which raises microorganism to decompose pollutant in wastewater. This treatment is suitable for wastewater from communities, municipalities, industrials and industrial estates.
3. Sludge Treatment It treats sludge from Physical, Chemical and Biological Treatment by removing water from sludge. This sludge becomes drier and reduces in volume, which is easier to transport. The machines used in removing water from sludge are filter press, belt press or centrifuge. This sludge treatment is used for Wastewater Treatment Plant from communities, municipalities, industrials and used for sludge from Water Treatment Plant.
Wastewater Treatment can be categorized by sources of wastewater as follows:
1) Wastewater Treatment from Communities Most wastewater from Thailand’s communities has organic substances in the water resources, which has BOD at 100 milligrams per liter. Biological Treatment is an appropriate method, using bacteria in treatment. There are two methods as follows:
|Aerobic Digestion||Anaerobic Digestion|
|Aerobic Digestion is a treatment using bacteria to decompose organic substances in wastewater by adding oxygen into wastewater in order for bacteria to multiply and rapidly decompose. Bacteria will consolidate and sink to the bottom, gaining clearer water||Anaerobic Digestion is popular among communities since it is simple and has lower costs. This treatment uses bacteria to decompose organic substances without adding oxygen. This process takes a long time and byproduct is pungent gas, which causes odor pollution for communities|
2) Wastewater Treatment from Industrials Wastewater from industrial has more contaminants than from community. Types of contaminants depend on types of industrials. Biological Treatment alone is insufficient since chemical substances and solute cannot be eliminated by Biological Treatment. Wastewater Treatment from Industrials needs chemical treatment, which is complex, together with Physical, Chemical and Sludge Treatments.
Wastewater Treatment Plant Process
1. Pretreatment Prior to taking wastewater into the process, Pretreatment separates large solids to prevent them from clogging and damaging the pipes. The steps in Pretreatment include:
- Screening separates large solids with screen. There are two types of screen, including coarse and fine screen.
- Crushing is reduction of size or volume of large solids by passing the crusher to reduce the size prior to sending to Grit Removal Process.
- Grit Removal is elimination of sand by reducing flow speed of wastewater in order for sand to sink to the bottom.
- Oil and Grease Removal is elimination of oil and grease from households, canteens, restrooms, gas stations and some industrials by storing wastewater in tank for a certain period in order for oil and grease float to surface for removal.
2. Secondary Treatment It is designed to eliminate organic substances in forms of solute or colloid. It is also called Biological Treatment since it uses bacteria in decomposing organic substances. At present, Wastewater Treatment needs Secondary Treatment to improve the quality of wastewater to meet effluent standards. Biological Treatment has two categories, including:
|Aerobic Digestion||Anaerobic Digestion|
|Add sufficient oxygen into wastewater to prevent pungent odor and allows bacteria to reproduce and decompose organic substances at faster rate. Bacteria will consolidate and sink to the bottom of the sediment tank||uses anaerobic bacteria in decomposing organic substances. This method is time-consuming and has pungent odor|
3. Advanced Treatment Advance Treatment treats wastewater from the Secondary Treatment Process by removing heavy metals or some other germs, which cannot be eliminated in the Secondary Treatment before discharging to public water resources. Advanced Treatment is not widely preferred as the process is too complicated with high cost. Most users applying this treatment will be for recycle.