Municipal Wastewater Collection, Treatment, and Best Practices
Make no doubt about it, running a municipal wastewater facility is one of the most important responsibilities a municipality has for its citizens. In theory they all run on the principles that biodegradation from facultative and obligate bacteria organically contained in the wastewater discharge runs the plant. As a result, if a plant has appropriate capacity and typical or standard type of waste flow it will take care of itself. Somewhere there’s a commonly told joke that’s punch line is, “…and that’s the difference between theory and reality.”
The engineers are experts at designing municipal wastewater treatment facilities. The same is true of the construction firms that build them. Everyone knows that municipalities run smoothly, and outcomes are always assigned to the most experienced and accomplished non-political decision makers. While there’s another punchline for that one, like most businesses, decisions are made by well meaning people who are balancing conflicting constituencies, ideas for growth and an imperfect amount of information and uncertainty. That’s the long way of saying “you got what you got, and you’ll have to make it work.”
Here some other oversimplified statements. Wastewater is delivered to the municipal wastewater facility by a complicated plumbing system called the sanitary sewers. Sanitary sewers utilize gravity to carry the wastewater whenever possible and use pumps in lift stations to push it uphill to higher ground where the wastewater can rely on gravity to make it flow naturally again. The sanitary sewer lines are accessed through lift stations and utility access manholes. These are usually but not always separate from storm sewer lines and creeks that are meant to divert rainwater from flooding the streets and lawns, fields, and other properties. Then the wastewater goes into the municipal wastewater facility or lagoon system where the wastewater goes through a series of screening, settling, aeration, scooping off the top, sucking out the bottom, and other processes that remove the bigger and more concentrated fats, oils, greases, petroleum oils and lubricants; called FOGs and POLs.
The previous statements are for the most part, true, but because plant designs, construction are imperfect, and flow makeup and capacity vary in unpredictable ways, chemicals and biological wastewater treatments are necessary.
What is in Municipal Wastewater?
From homes there are more FOGs and starches like feces, urine, kitchen grease, vegetable peels, whatever goes down through the garbage disposal, toilet paper, tissues, dish and clothes washing detergents and lots more that all discharge through a “lateral line” that connects up with the sanitary sewer. What happens in the lateral line is the homeowner’s responsibility to maintain.
A factory is more likely to discharge POLs although they do also carry many of the FOGs similar to home wastewater. Industrial petroleum greases, compressor and coolant fluids, contaminants of heavy metals, glue and bonding agents, dirt, dust, cleaning solutions and a lot of other industrial waste. In food processing plants and kitchen, commissary settings there is a lot of organic matter and FOGs. Many factories will either pretreat their discharge or store it in lake like holding areas called polishing ponds.
Schools and hospitals tend to discharge FOGs in high ratios. They also use cleaners, detergents, disinfectants, drain openers, other types of organic human discharges like blood, plasma and the list just continue. They have kitchen, cafeterias as well as ice machines, operating theaters, mortuaries, boiler blowdown, HVAC condensate, art room soils and paints and more.
How Does Biodegradation in a Municipal Wastewater System Work?
Most municipal wastewater has solids, contaminants and largely organic matters that need to be broken down into smaller molecules and eventually fully digested by bacteria. These organic wastes already have bacteria and enzymes that facilitate the natural process of biodegradation. Primarily these are in four categories of waste degrading bacteria and enzyme compounds: Amylase, Protease, Cellulace and Lipase. These cells attach themselves to the waste in the water and penetrate the waste molecules through a polysaccharide shell, a one-way entrance into the cells center. Then the enzymes catalyze the bacteria to split the cell into two cells and release CO2 by the process of binary fission or mitosis. Those two repeat the process and make four waste eating cells. It takes tens of millions of these waste degrading cells to break down the waste so high-count non-pathogenic bacteria must be woken and catalyzed to break down the waste in municipal wastewater.
Why Do Municipal Wastewater Facilities Smell Like Rotten Eggs?
The primary reason is as wastewater is biodegrading the byproduct of binary fission or mitosis is methane gas. You’ll often find this rotten egg smell at corporate farms where they dispose of cow, hog, chicken, sheep feces, etc., in their own waste treatment facilities, which work upon the same principles as a municipal wastewater treatment facility. It is rare for a facility to have the smell of a particular waste like feces or other organic or inorganic waste because they are so diluted by the water that carries it from homes, schools, and businesses that odors come from the mitosis and not the waste itself.
How Do Municipal Wastewater Treatment Professionals Keep the Sanitary Sewer Lines from Clogging and the Plant from Being Overcome with More Waste Than They Can Manage?
Keeping the sanitary sewers from becoming clogged requires general preventative and declogging processes. Most wastewater departments have a “sewer jetter” which is a high-pressure washer they can put into a utility access hole and fuel it with hydro or waterpower. They run water into the machine which compresses it into both a strong spray to knock debris off the walls of the sewer lines and to propel it forward. They either pull it back or detach it at the next manhole and reattach the water source to move it on down the line. They will also use industrial degreasing products like Continental Research’s Mighty Foam. Often there are tree roots and other plants that grow through the cracks to reach a water source that may be broken and rinsed down the line while using a sewer jetter. Finally, when all else fails the fire department will lend a hand and use their equipment to flush a lot of water down the sanitary sewer line.
Are There Any Other Areas Where Municipal Wastewater Departments Pretreat Can Improve the Performance of the Collection System?
Most collection systems have choke points where it's twisted and turned, where the waterflow is not sufficient to move waste to the wastewater facility. Here, you can remedy this issue by hanging a bacteria block like Continental Research’s Bacto Brik from a stepladder in a manhole to add some early biological surge. In lift stations, products like Bacto Dose, Surge 100X, Prime, Soy Orange Float, and Grape Idea are highly effective. Often, a municipality will create a building code requiring restaurants to have grease traps and factories to put in pre-treatment chemicals or even a small pre-treatment plant, lagoon or polishing pond.
What Chemicals Do Municipal Wastewater Treatment Plants Use at Their Facility?
The plant scenario we outlined earlier does do a solid job of operating with the organic bacteria and enzymes in the wastewater itself. But the process of accelerating the degradation of wastewater is facilitated with additional bacteria such as Prime, Surge 100X, Bacto Dose, Air-8, or Now ‘n Later. A wastewater facility is also a laboratory and requires reagent testing for harmful byproducts like nitrites, heavy metals, and other substances. They are also a shop as well as having a fence surrounding the property, so no foul play, vandalism or terrorist activities take place. They’ll use plenty of lab supplies, bench chemicals and weedkillers to maintain the facility and reduce labor man hours.
Where Does The ‘Sludge’ in a Municipal Wastewater Treatment Facility Go?
Once the sludge from municipal wastewater is removed, it’s taken to a sludge dewatering bed or a sludge press where it is allowed to dry. In many rural communities’ local farmers can collect it and use it as a fertilizer or a fertilizing catalyst. Some is taken to landfills. For the most part it is inert and no longer has odors or active ingredients that could be harmful to people or wildlife so parks will take it and mix it into their mulch farms.
Are the Chemical Additives Used in Municipal Wastewater Treatment Harmful?
Certainly nothing sold in an industrial package is meant to be ingested by humans or wildlife. However, when used according to label instructions, following the dosage guidelines, and using proper safety equipment, the chemicals used by professionals in municipal wastewater treatment facilities is less harmful than the wastewater itself. While not a blanket statement - some industrial solvents, declogging chemicals, or weedkillers that are meant to be used by trained professionals can in fact be dangerous. We like to say, “It’s like the Zoo. You’re safe if you don’t fall into the cage!”
For the best municipal wastewater treatment solutions, professionals prefer the Continental Research brand of wastewater treatment products. We make your job easier - simply Request a Quote or Ask an Expert and you will be working with the best wastewater treatment solutions available.