Understanding Sewerage Treatment Systems

08 June 2018

Sewerage treatment systems thoroughly scrub waste from citywide waste streams. That being said, there’s no single technological approach that will filter and neutralize this noxious human byproduct. In lieu of such a singular solution, numerous processes work together to effectively eliminate the waste. Starting with the pre-treatment stage, let’s see where the chain of sewage-eliminating actions flows to before that fluid can safely reenter the local environment.

The Preliminary Chores

A purely physical chain of threshold mechanisms starts the work. They’re located in catchment wells and screening zones. It’s here that leaves and rags, sanitary towels and wet-wipes, and all other heavy waste is filtered. Often overlooked by drainage designers and infrastructural engineers, this important stage exists to prevent system clogs and potentially unhealthy stream backups. After all, this semi-solid mass of city ejects is loaded with bacteria and rotten material. It cannot be allowed to enter the environment, not until it has been properly treated.

Sewage Treatment Farms

Here’s where the bulk of the treatment process is carried out on the river of bacteria-laden effluent. Pumping stations and ejectors are hard at work. Some even have secondary maceration stages, all the better to really break up those semi-solid deposits. Now the waste is filling several special wells. Next, the natural laws of fluid dynamics get a helping hand. Those organic actions need to be speeded up a little. Solids settle to the bottom of the pit, the wastewater stays up top, and sediments take form. An additional sedimentation tank even separates grit and small stones from the mix. Beds of stones and screens further filter the wastewater, but the heavy sludge is left behind, perhaps for use as biofuel.

Second Stage Sewage Processing

A casual observer would guess at chemical detergents and aggressive bacteria neutralizing agents, but nature is still in charge of the treatment. The stones and grit filter the wastewater, the bio-solids are out of the equation, and we’re moving onto the next stage. In here, anaerobic bacteria combines with oxygen to digest the partially processed sewage. Basically, the harmful bacteria is killed and shuttled into a clarification chamber, then the remaining water is further treated until it’s released back into the city waterways, fully processed and safe to consume.

Technical services reserve resources when they’re dealing with sewerage treatment plants. These “farms” are formed as physical filtration and catchment mechanisms before the waste stream ever reaches that treatment centre. Pumping stations and maceration units further break up the sewage, then grit and stones combine with anaerobic digestion tanks to entirely kill the harmful bacteria. Lastly, important venting systems need to be in place here, for there are methane and hydrogen sulphide clouds being discharged from the organic matter.

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