Thursday, July 2, 2009

Waste Water treatment- the basics

At SES we provide our customers with knowledgeable experience in many processes. One of the services we provide is designing, setting up, and maintaining waste water treatment systems. Below you will find information on the various elements used to remove metals from waste water and how they accomplish this task.
1. Equilibration tank -
Using a holding tank which will allow various streams with various contaminants to mix together and equilibrate. This enables the treatment unit to address the entire mix rather than each stream individually. Exceptions to this procedure are situations where cyanide is present (requires pretreatment before mixing) and situations where large amounts of hydrocarbons are present. Phase separation or acidification is required then to pre-treat and remove the hydrocarbons. Once the hydrocarbons are removed and there is no cyanide left, the treatment process for metal removal can begin. After the equilibration step the water is pumped or flowed into a reaction chamber or mixing tanks.
2. Reaction chamber and mixing tanks-
Mixing chambers are used in convent ional systems to add acids, caustics or lime for ph adjustment, reducing agents for conversion of species by oxidation or reduction i.e. Chromium. Most mixing chambers or tanks enhance the process by stirring, and chemicals are usually added by diaphragm or metering style pumps. One of the desired results of the mixing of the water and reagents in the process is to generate a solid precipitate particle which incorporates the contaminants inside and which then can be removed from the resultant clear water stream by flotation or settling. Polymers are used to enhance this separation process. Once the particulates are formed and flocculated with the polymer the water is allowed to flow into a clarifier.
3. Clarifier-
Clarification is enhanced manually by flowing the water/ particulate mixture through an inclined plane clarifier. This process allows the particulates to agglomerate even more and become a loose sludge. As the sludge forms the clear water continues to move up through the system and out to discharge. The sludge mentioned above requires further concentration. It is pumped from the bottom of the clarifier into a sludge thickening tank by double diaphragm pumps.
4. Sludge thickener-
Sludge thickening is done in a sludge thickening tank which may be outfitted with a very slow center mounted stirrer. The sludge from these tanks is pumped into a filter system to further concentrate the sludge and dewater it to free up the clean water.
5. Water discharge- Is accomplished both from the top of the clarifier, and from the filtrate from the filter press or filter system.
6. Filter press-
Sludge processing is best done by filtration and dewatering or drying. This can be accomplished with filter presses, gravity filtration boxes, sock filters, or drying beds.

SES can supply, all of the materials for each of these processes, as well as design, construct, and maintain a waste water treatment plan to best suit your needs. For more information please call us at 210-633-0051.

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