General Principles of Sewage Treatment

General Principles of Sewage Treatment

Raw sewage and septic wastewaters contain a variety of contaminants. Many technologies are available to render the sewage suitable for safe discharge to the environment. These include those used in the municipal treatment works that receive sewage discharged to public sewers in the nation’s developed areas; conventional on-site sewage treatment that uses a septic tank and soil absorption field commonly used in rural areas; and the alternative on-site technologies that form the focus of this publication. Most sewage treatment technologies operate by combining basic physical, chemical, and biological processesSurface Aeration - Waste Water Treatment
1. Primary treatment removes solid chunks and particles from raw sewage through gravity separation and/or screening. A septic tank is the most common primary treatment device in on-site systems. In alternative systems, the septic tank is commonly outfitted with an outlet filter, to capture solid particles that are too small or too light to settle. When used with conventional septic systems, an outlet filter will extend system longevity and improve performance. The partially-treated liquid discharged from primary treatment is called primary effluent.

2. Secondary-treatment processes (also called microbial digestion) receive primary effluent. Most secondary-treatment processes move the effluent through an aeration process environment that is favorable to aerobic microorganisms, those that thrive in atmospheric oxygen (O2) environments. The following wastewater renovation processes occur during this treatment:

Pathogenic microorganism populations are reduced. The vast majority of microorganisms found in sewage thrive within the human digestive system, an environment where oxygen does not occur as O2. Consequently, these organisms are not well adapted to aerated environments. Within secondary-treatment devices, some microorganisms (including most pathogens) perish as a result of exposure to O2.

Other organisms, including predators that consume pathogens, do thrive in an aerobic environment, sustained by the rich mix of O2 with H2O, biodegradable organic compounds, and essential nutrients that comprises sewage. Where the effluent passes through secondary treatment media with small pores (such as a sand filter, or natural soils), pathogen numbers are also reduced via physical straining.

Biodegradable organic contaminants, such as dissolved organic substances, and organic particles, remaining in the effluent after primary treatment are removed.
The microorganisms in the aerated secondary-treatment medium consume and metabolize biodegradable organic compounds, deriving energy by breaking the carbon-carbon bonds and converting the organic carbon to carbon dioxide (CO2).

Small particulate contaminants are removed. Where the filtration media are comprised of mineral particles with small pores (such as a natural soil or a sand filter), particulate contaminants are removed via physical screening; biodegradable components of the particles captured in the fine pores are consumed by the resident aerobic bacteria. wastewater treatment via surface aeration
The partially-treated liquid discharged from secondary treatment is called secondary effluent.

3. Advanced treatments are optional processes that may be applied to remove additional contaminants from secondary effluent prior to dispersal. Advanced treatment is usually included only in systems intended to discharge directly to the land surface, or to surface-water streams. Advanced treatment processes designed to remove additional nitrogen and phosphorous from the effluent are sometimes necessary to protect water quality in streams receiving treated effluent discharges.

4. Disinfection systems often rely on chlorination, ozonation, or ultraviolet light. Systems that discharge treated effluent where there is a potential for direct human exposure (i.e., discharge to surface waters or the soil surface) are often required to disinfect the effluent so as to eliminate potential hazards due to human exposure.
Effluent that has been disinfected, and has received advanced treatment, is called tertiary effluent.
Treated effluent must be discharged to (or dispersed in) the environment. Secondary effluent is commonly dispersed in soils below the surface, while tertiary effluent may be discharged to flowing waters (such as a surface-water stream) or on the soil surface. Surface discharge or dispersal typically requires a permit from an agency responsible for protecting surface-water quality as well as an on-site septic system permit. Credit:https://www.slideshare.net/ricardo0hodges91/ onsite-sewage-treatment-alternatives-publications-and-educational-resources

Laser Teeth Whitening

Laser Teeth Whitening

A number of people have teeth that look dingy and yellow. Some search for treatments meant to improve the whiteness. Laser teeth whitening is a major technique used to whiten teeth. It is advisable to consult your nearby orthodontic dental clinic for the right method for you. Most dentists use this method to whiten or bleach the teeth. It is important to note that healthy teeth play a great in maintaining your overall health. The method has gained popularity simply because it is painless, quick and efficient. If you want to whiten your for the very first attempt, this is the method that will get you quick results.Teeth whitening

This teeth whitening procedure has a lot of benefits to the patient. It is an elective cosmetic procedure, which uses laser technology combined with an agent, which is activated by laser light to remove the stains from your teeth. The result is bright, clean and white teeth. This is a method suitable after basic toothpaste and various teeth whitening products have failed. It is the method for those who want dramatic results. The following are some of the benefits offered by this method:

· Quick and painless. The procedure can be done in the office of your dentist or at a local dental clinic. This just takes a single visit and it will be done in less than an hour to complete. On the other hand, the teeth whitening kits you take home, no matter whether they are from a dentist, will be worn for some weeks to note positive results.

· The cost of this procedure is low. However, this depends on type of treatment you choose. It is advisable to consult your doctor to get the exact cost and whether there are before and after charges.

· The procedure is less damaging. Weakening or softening of gum line and teeth do results from teeth bleaching. This is greatly attributed to improper use of bleaching products sold over-the-counter.

· Protection against sensitivity. During the procedure, a rubber shield or neutralizing gel is placed on gums in order to protect the gum against sensitivity.

Before you undergo the procedure, it is important to understand the side effects as a result of laser teeth whitening procedure. Fortunately, these side effects are minor and commonly regarded as undesired side effects. Usually, the undesired side effect is increased sensitivity of the teeth or the surrounding tissue. After the procedure, you will feel some extra sensitivity and irritation. This can increase when drinking cold or hot beverages. However this will dissipate quite quickly. To avoid this, the dentist covers your gums to avoid being in contact with laser light or whitening agent.Pearly Whites

Your smile can mean a lot of things. It is one of the things people notice about you. Consequently, your smile should be white and bright as possible. Laser whitening is the best method to provide you with these benefits to help you show off beauty of smile. This will not be possible without making your teeth sparkle. If you are living in Montreal, laser teeth whitening will provide you with extra edge needed to stand out in a crowd.