The Importance of pH Control in Biological Wastewater Treatment

The Encyclopedia of Ecology defines biological wastewater treatment as a process where “organisms assist in environmental cleanup through their own life-sustaining activities.” Instead of treating water with chemicals, algae, beneficial bacteria, fungi, metazoan, and protozoa are all microorganisms used to feed on the organic material, which is important to their lifecycle and also helps clean the water.

But, as microorganisms eat these materials, they produce methane and carbon dioxide. The resulting odors make it a less-than-desirable process for anyone living downwind of a wastewater treatment facility. This is a leading reason pH control is an important part of biological wastewater treatment.

The Benefits of pH Control in Biological Wastewater Treatment

A balanced or neutral pH is 7.0, but pH can range from 0 to 14. If it is higher than 7.0, wastewater is acidic and needs to be lowered. If it’s over 7.0, it’s alkaline and needs to be lowered. 

Before treatment begins, raw wastewater usually has a pH as low as 6 or as high as 8. When it’s high, it’s often caused by too much algae growth in open wastewater lagoons or the wastewater is already high because of industries that use lime, lye, or sodium hydroxide.

A low pH is often because of high ammonia levels. It’s the most common problem wastewater facilities face when they use activated sludge systems. By making sure you keep the pH balanced, your plant benefits in several ways. 

Heightened Efficiency

Plants with a healthy pH work efficiently. They’re less likely to run into imbalances that require extra effort to repeat water treatment steps to remove extra sludge, increase aeration, and grow healthy colonies of microorganisms. You treat water faster, better, and more cost-effectively.

Reduced Sludge Production

When your wastewater has a balanced pH, sludge production lowers and sludge disposal costs drop. You have less sludge to compost, incinerate, or haul to a landfill, which means you save money.

Improved Removal of Organic Matter

Healthy microorganisms remove more organic matter. When water is treated quickly, it lowers your energy consumption and saves your plant money. You’re also not releasing treated water to area lakes, streams, and rivers before it’s safe, which can lead to massive fines for raw sewage releases.

You’re not sacrificing quality for savings. You get both, which makes everyone happy.

Compliance With EPA Regulations

When a permit is issued, every wastewater treatment plant has EPA standards they must meet before releasing treated water to a water treatment plant for reuse or to a local body of water. If you’re not in compliance, the EPA can issue fines.

Fines for negligent violations range from $2,500 to $25,000 per day and up to a year in prison for the first violation or two years and up to $50,000 from the second year on. 

Intentional violations have fines of $5,000 to $50,000 per day and a 3-year sentence. Subsequent violations increase the fines to as much as $100,000 per day.

If a wastewater treatment plant violates its limits due to the acts of an industry that violated pre-treatment, the industrial business can be fined. It’s just as important for a company to pre-treat any industrial wastewater. In 2023, a beef processing plant in Nebraska paid $275,000 in fines for failing to properly treat its wastewater before releasing it. This wasn’t the first time, the company paid $1.2 million in fines in 2011.

What Happens if You Don’t Control Your Wastewater’s pH?

A lot can go wrong when you’re not monitoring and correcting your wastewater’s pH.  The microorganisms you use will slow down and grow at a slower pace. That allows harmful bacteria to increase their activity. As the balance of microorganisms and bacteria become imbalanced, your wastewater treatment plant loses stability. You’ll end up having to start over to have a thriving colony of microbes again.

Because your microorganisms aren’t thriving, organic matter and pollutants aren’t effectively removed from your wastewater. Sludge increases and becomes harder to get out of the wastewater, as it doesn’t settle as quickly.

Imbalanced pH levels can also corrode your equipment and damage your municipality’s infrastructure. It also puts area waterways at risk of contamination and problems with algal blooms, which harm the wildlife and aquatic life.

Plus, you face the fines from the EPA as listed above. Having properly treated wastewater is important before you release wastewater into a lake, ocean, or other body of water. You need a system that works quickly, correctly, and handles higher flow rates.

The EPA fined a Massachusetts wastewater treatment plant $200,000 for combined sewer overflows when heavy rain increased flow rates. As they’d been fined back in 1988 for the same issue, they must spend $200 million to separate their sewer and stormwater runoff systems. 

Tips for Maintaining Proper pH Control 

How do you ensure you have the right pH in every stage of wastewater treatment? There are several things to do. It’s not a one-size-fits-all situation. Your wastewater treatment plant’s flow rates and contaminants play a role. A wastewater treatment plant dealing with mainly residential wastewater will have different needs than one surrounded by restaurants and businesses.

Add Acids or Alkalis 

When the pH is too high, acids need to be added. Plants may use carbon dioxide or sulfuric acid to lower the pH. If the pH is too low, lime or caustic soda are possible additions.

Add Buffering Agents 

Once the pH levels are balanced, they need to be stabilized. This is done with chemicals like carbonates or phosphates. Ideally, you want to take steps that stabilize pH from the start. Optimizing wastewater treatment processes is ideal.

Implement Real-Time pH Measurements 

Plant automation saves a lot of time and hassle. Look into sensors that continually measure pH, temperature, dissolved oxygen, and other important aspects listed in your EPA permits. When you have real-time information on your wastewater’s quality, it’s easy to take corrective measures to maintain proper pH control.

Optimize Your Plant’s Processes

Instead of needing to use things like lime or sulfuric acid, optimize your plant. Aeration, organic loading, and establishing healthy levels of nutrients are important. This requires having the best equipment with aerators, real-time monitoring, screening, and filtration. 

If you’re aiming for a functioning, effective biological wastewater system, you need the best equipment for the job. Talk to Lakeside Equipment, experts in clean water, to find out what your plant is doing well and what will help ensure your pH levels remain balanced and keep your system in perfect order.