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Imperial’s $21M Sewer Plant Goes Online

High-Tech Treatment Already Improving Quality of Life for Residents

The aeration basin, one of several basins where microorganisms are added to break down organic solids within wastewater, bubbles as wastewater plant operators add oxygen to the water to keep the microorganisms alive so they can do their work. The process was shown during a tour of the city of Imperial’s new $21 million sewer plant on Thursday, Oct. 14. | MARCIE LANDEROS PHOTO

IMPERIAL — Dealing with sludge in the wastewater treatment process — human waste in its concentrated form — can be a smelly and messy business, yet the whole ordeal just became a little less gross in the city of Imperial where its state-of-the-art sewer plant has gone online.

Plant Chief Operator Christopher Kemp described Imperial’s new “membrane bioreactor” wastewater treatment facility as the most advanced treatment facility in Imperial County.

“No one, none of the other cities in the Valley, have anything like this plant,” Kemp said of the facility that went online about 30 days ago. “We used to have to take the sludge over and spread it all out to dry. It made a mess of flies and smelled bad, but not now.”

At the end of the wastewater treatment process, clean, clear water is drained into the waterways of the Imperial Valley. The end result of the process was shown during a tour of the city of Imperial’s new sewer plant on Thursday, Oct. 14. | MARCIE LANDEROS PHOTO

Imperial’s new facility has been outfitted with a membrane bioreactor, which uses part of the traditional activated sludge process that most wastewater treatment plants use in which solids are dissolved into a sludge by microorganisms and left to dry outside before being disposed. This process is what creates the smell and pests associates with conventional sewer plants.  

The membrane bioreactor uses this same process but adds a membrane that holds the solids to dissolve them faster, and microfiltration through the membrane removes more of the biological solids with less water. Next, the filtered solids are separated so that they can be moved into another part of the plant once they have been properly dissolved so they can have the moisture removed further, with another machine called a corkscrew press. 

Eddie Guzman, an Imperial resident who lives a few blocks north of the new plant at 612 N. N St., said there is already a change in the area’s quality of life.

“Man, there used to bugs all kinds, and I hated the smell. Whenever I would open my door for the first time to go to work, I would always brace myself for the smell,” Guzman said on Sunday, Oct. 17. “Yesterday, when I went to work, I don’t know, it was like I braced myself for nothing.”

Guzman said that the smell and the insects the wastewater treatment plant had produced was a source of tension within his household.

“My wife hates it. She is always complaining about the smell and the bugs. If this new plant really does keep the smell and bugs down like this, I might finally not have to hear about it anymore,” Guzman said with a laugh. “Let me tell you, that is enough for me to think that the $21 million was worth it.”

This $21 million project was 15 years in the making, according to Imperial Mayor Karin Eugenio. The sewer plant has gone from treating 2.4 million gallons of wastewater a day, to treating 6.3 gallons a day — to prepare for the city’s 23 percent growth rate, Eugenio said in a statement.

“With projects to the north, including the completion of the abandoned hotel, McDonalds, Starbucks and multiple housing subdivisions to the east, west, and not of the city center, this treatment plant will prove indispensable,” she stated.

At the new facility’s current capacity, the city should be good for at least 50 years, Eugenio said in a brief interview on Tuesday, Oct. 19.

Sewer rates were raised to pay for plant back in 2015, she said, adding that no further rate hikes are planned that are directly tied to the new construction.

“We outgrew (the old) facility in 2007. It’s just been Band-Aids over the last decade to consistently keep up with the needs,” Eugenio added on Tuesday.

The corkscrew press that operates at the city of Imperial’s membrane bioreactor wastewater treatment plant removes excess moisture to reduce drying time, odor, and pests from sludge is shown during a tour of the facility on Thursday, Oct. 14. | MARCIE LANDEROS PHOTO

“With projects to the north, including the completion of the abandoned hotel, McDonalds, Starbucks and multiple housing subdivisions to the east, west, and not of the city center, this treatment plant will prove indispensable,” Eugenio stated.

Since the first cities, dealing with human waste has been a problem that has confounded society. During the Industrial Revolution, “communal privies” — public outhouses, for lack of a better term — were regularly used to collect waste, which were then removed from the city, usually taken to farms to be used as fertilizer.

With the invention of modern plumbing, most people stopped concerning themselves with what happened to their waste once it left their house.

The city tried to provide a small window into that process when it opened up its new wastewater treatment plant to tours on Thursday, Oct. 14, where Kemp explained the technology behind the facility.

To collect the solid waste after the squeezing process, the waste is pushed up a shoot which comes out of the side of the building, then forces the waste into a pile so that it can be raked into the drying area to finish drying. The process was shown during a tour of the city of Imperial’s new plant on Thursday, Oct. 14. | MARCIE LANDEROS PHOTO

In this new facility, wastewater — whether it be what is flushed down our toilets or what washes down our drains and gutters (referred to as gray water, in those cases) — first goes through a process where non-dissolvable solids, like rags or eggshells, are spun out of the water and thrown into shoots which lead directly into trash receptacles to be properly disposed of by Republic Services, Imperial’s solid waste contractor.

Next, the wastewater is moved into basins and mixed with microorganisms, nicknamed “bugs” by wastewater professionals, that breaks down the biological components by digesting them until that “slurry” has turned into a thick sludge. This sludge is the source of much of the issues wastewater plants face, as the high moisture content before it dries makes it perfect for pests and odors.

To combat these issues, the new plant uses the membrane to capture and concentrate the solids, and effectively filtering the water until it is clean enough to be drained into Imperial Valley waterways.

The solids are flushed into a corkscrew press, the only one in the Imperial Valley,  according to Kemp, which compresses the solids, squeezing the water out of the sludge, removing most of the moisture and significantly cutting down the pests and the smell.

Once the solids are pressed, they go through the some drying before being disposed of through Republic Services, but the time required to dry and being exposed to the elements is much shorter.

In building up interest in the city’s new sewer plant, Mayor Eugenio posed a fundamental question about life after the flush: “How many people actually think about this process? The reality is: what would the quality of life be without the tireless efforts achieved by … our dedicated (public works) employees every day?”

Once filled with the liquid sludge the wastewater plant used to produce, these drying areas now finish drying solid waste that has had the moisture squeezed out of it in the corkscrew press. The process was shown during a tour of the city of Imperial’s new $21 million sewer plant on Thursday, Oct. 14. | MARCIE LANDEROS PHOTO
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