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Wastewater: Complex, Highly Regulated, and Costly

Where your dollars go: it's not just down the drain.

Post Date:04/02/2019 2:00 PM


When you are dealing with wastewater, most people just want to flush or rinse then walk away. They don’t want to worry about what happens to the stuff that they flush down their toilets or rinse down their sinks. But the fact is, after this waste leaves your home, it all becomes a very complicated and expensive process of treating and turning it into a safe product that can be reused and released into our environment.

Wastewater treatment is highly regulated by the U.S. Environmental Protection Agency (EPA). EID’s permits are issued by the Central Valley Regional Water Quality Control Board (CVRWQCB). The permits are specific to each treatment facility where stringent testing, monitoring and treatment processes are required. It’s all done to protect us and our environment.

EID works very hard to keep the expenses down by working with regulators, hiring experienced and highly trained staff, and diligently maintaining approximately 386 miles of gravity sewer pipelines, 55 miles of pressurized main lines, 9,372 maintenance holes (manholes), and 60 lift stations.

EID’s system is unique and extremely complex, especially if you compare to neighbors like Folsom or Sacramento. EID’s foothill location presents unique challenges to safely convey sewage from customers’ homes and businesses to the treatment plants. The hilly terrain means that some of the flow must be pumped multiple times before reaching the treatment facility. And the District has a smaller population base to spread the costs of regulatory upgrades and maintenance.
Required Standards
EID is required to treat wastewater to tertiary standards. This means that the water from your toilet, sink, dishwasher, shower, and washing machine is treated to the extent that it can be released back into the environment or put to beneficial uses such as water for fire or dust suppression or utilized as recycled water for irrigation purposes.

Some treatment facilities are only required to treat to secondary standards. This practice is changing though: regulations will soon require secondary wastewater treatment processes upgrade to tertiary standards. It will cost millions and millions of dollars for those plants to be brought up to the same processing requirements that EID has had for more than twenty years.

Wastewater treatment is accomplished through a series of physical and biological processes followed by a disinfection step. Science and biology play a big role in wastewater treatment.

First, the wastewater is screened using mechanical equipment to remove debris larger than a quarter inch in diameter. Unfortunately, many things that come down the pipe should never have been put down the drain in the first place. So-called “disposable” cleaning cloths like flushable wipes are a good example. It requires extra time and money to remove these products, and then properly transport the debris to a landfill. Simply disposing of them in the trash instead of the sewer not only results in a cost savings for the treatment plant, it can help the reduce vehicle emissions and impacts decreasing the number trucks making trips to the landfill.

Not putting these items in the sewer system helps protect your pipes, the community, and helps keep the costs down on the processing end.

Primary Treatment
After the wastewater is screened and the sand and grit is removed it continues into a primary clarifier or sedimentation basin, where the physical process of slowing the flow allows floating and suspended material to be separated. At this stage about 60 percent of suspended and floating material is removed.

Secondary Treatment
This is where dissolved and organic materials not removed with primary treatment are now removed. This is where the biology comes into play. With the use of bacteria and other microorganisms, these materials are broken down into organic matter called activated sludge. In this process, microorganisms feed on organic contaminants in the wastewater, producing a high-quality effluent.

The secondary treatment process is biologically sensitive and the microorganisms like their environment to be free of inappropriate products and toxins. This is why we promote binning materials like medications that should not be introduced into the sewer system.
Tertiary Treatment
This is where the wastewater is filtered and the majority of the remaining suspended particles are removed; it’s like a polishing process. The filtration process is similar to the process that our drinking water goes through. But this is not the final process in treating wastewater that will be either released into a creek or reused as recycled water for irrigation.

Ultraviolet (UV) disinfection is the last and final step in the process. It’s the process that destroys pathogenic, or disease-""producing, organisms making the former waste product into a valuable resource: a renewed and reusable commodity.

EID's website has more information about wastewater treatment, recycled water, and tips for how to dispose of materials that should not be introduced into the sewer system.

This article was published in the March / April issue of EID's bimonthly customer newsletter The Waterfront. To read past issues of the newsletter visit The Waterfront Newsletter & Archive webpage.

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