Municipal Wastewater Treatment Plant Efficiency

The U.S. Department of Energy found that the annual expenditure on energy used by the nation’s wastewater treatment plants exceeded 30 terawatts. That equates to 30 billion kilowatts. The cost of all that electricity comes to just over $2 billion using average 2020 electricity rates.

Electricity makes up about a quarter to half of a wastewater treatment plant’s budget. To keep costs down, municipal wastewater treatment plant efficiency must be a top priority. Not only does it reduce energy usage, but it also helps make sure a plant is meeting the needs of the growing population. An efficient plant can help reduce downtime from maintenance and repairs with upgraded equipment.

Establish a System for Energy Management

Start by establishing an energy management system. ISO 50001 says that an energy management system is a set of policies and objectives to help manage energy followed by the steps taken to follow through and continually monitor and manage energy use.

You need to understand what uses energy within your plant. Think about office equipment, water treatment equipment, fans, and lighting. Pay close attention to the things that use more electricity than others. Older equipment is going to be less efficient than newer ones. Even little changes like upgrading fluorescent lighting fixtures to LED ones help you start saving money. Consider every part of your plant to start creating a comprehensive blueprint of what’s in your wastewater treatment plant and how much energy it uses.

Leaders within the municipality should create energy-efficiency and cost-cutting goals as they look at everything within the plant. Start coming up with ways to meet those goals and commit to the measures that need to be taken. Do not be unrealistic. It’s hard to make something happen if the odds are already against you. Upgrading all of your aerators, pumps, etc. may be ideal, but if you’re short on money, it’s not realistic. Instead, look at things other plants have done that worked well, get a better understanding into how much those changes would cost, and see if you could make that work for your municipality.

If you plan to reduce electricity consumption by 25%, start looking into the ways you can make that goal happen. You might want to offset how much power you get from the local power plant by adding solar panels to your wastewater treatment plant. Maybe upgrading to newer aerators or pumps will help you reduce energy use by 35%. If that would work, start researching the cost of new pumps versus the savings you’ll gain in the next months and years. Often, upgrades pay for themselves in a year or two.

Equipment Upgrades That Improve Efficiency

There are two ways to approach upgrades. Improve performance and it reduces your operating costs. Something as simple as a new grit removal system can lower costs by allowing for the highest level of aeration and improving the volume in digester tanks, both are essential steps in wastewater treatment.

Automate your plant and you’ll save money. When you have equipment that is automating the process, it lowers power consumption. A process control system monitors the different stages of wastewater treatment and can lower pump and motor speeds. It wastes energy if you have pumps running at full speed at hours when incoming wastewater from sewers and septic haulers is barely flowing.

Wastewater often contains grit. That grit can be sand that’s rinsed off after a day at the beach. Coffee grounds that get rinsed from cups and reusable coffee filters. Small food particles that go through a garbage disposal also can lead to grit. Some wastewater treatment plants see an average of more than 13 cubic feet of grit remaining after treating a million gallons of wastewater. That grit can impact efficiency and cost your plant money in repairs and maintenance. A high-quality grit removal system improves efficiency and reduces wear and tear on parts within wastewater treatment equipment.

Lakeside Equipment specializes in high-efficiency screw pumps. They’re designed to be efficient and lower your electricity costs for the entire life of the screw pump. There are enclosed and open screw pumps. Open screw pumps are designed to be up to 75% efficient. Type C enclosed screw pumps are up to 86% efficient, while Type S enclosed are up to 75% efficient.

Alternative Energy Sources

Look at ways to power your wastewater treatment plant that doesn’t rely solely on grid electricity. What are your options when it comes to renewable energy? Here are the two most common options and their pros and cons.

#1 – Solar Power

Solar power requires panels that are installed either on a roof or on supports on the ground. The panels capture the sun’s rays and convert them to a DC current that’s sent to an inverter where it is converted to AC power. That power is used to power the plant. If any is left over, it’s sent to the grid. Solar power generates on cloudy days but not at the same rate as on a sunny day.

Solar is expensive starting out, but energy-improvement grants and leasing programs may help. Talk to your local electricity company for advice on what programs are available. Some are strictly for residences, but others consider plants and businesses.

Snow covering the panels will temporarily stop production. Some solar companies recommend that you don’t clear the snow, especially if you’re leasing the panels. If you live in a snowy region, you may need to pair solar with your city or town’s grid electricity. This can be one of the biggest downfalls to solar.

In 2019, a 137-kilowatt/hour solar array was installed to provide power to the Sprague Wastewater Treatment Plant in Connecticut. That array is estimated to meet 80% of the plant’s electricity needs. Some of the energy is sold back to the town to help cover the initial cost.

On average, solar panels have a lifespan of 25 to 30 years before their production dwindles. Once they no longer produce, they have to be replaced. Recycling solar panels is still a new process. Components include metal, photovoltaic cells, plastic, glass, and silicon or film that covers the panels. Recycling takes time and training to break down the different components. Few states in the U.S. have policies regarding solar panel recycling. Europe is a leader in solar panel recycling, but it’s expensive to ship them overseas. You have to consider what it will cost to dispose of the panels at the end of their life.

#2 – Wind Power

Windmills or wind turbines have been around for over a century. When the wind blows, it moves the blades. Those blades are attached to a rotor that spins a generator to produce electricity. That electrical current goes to a transformer where it is converted into a voltage that travels through electrical lines to the grid that’s used to power the wastewater treatment plant.

Rhode Island’s Field’s Point Wastewater Treatment Plant paid to have wind turbines installed. The $14 million installation may seem like a lot, but the power generated by the three wind turbines cut the plant’s electricity bill by over $1 million a year.

Wind power is one of the most cost-effective forms of renewable energy, but you need space for the turbines. They can be noisy and not everyone finds them appealing to look at. That can draw complaints from homeowners who live close by. That can make it difficult to get the permits needed. The other drawback is that wind isn’t a constant. A stretch of non-windy days will affect production.

Partner with Lakeside Equipment to discuss, plan, and install equipment upgrades to improve your municipal wastewater plant’s efficiency. Our engineers and sales team have decades of expertise in the best ways to lower energy costs while considering population growth and quality wastewater treatment at the same time.