Wastewater treatment

Air compressors can be power-hungry and inefficient. Here’s how Atlas Copco can help you to look out for your budget and energy costs when selecting your compressor.

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Using Air Compressors in Wastewater Treatment and Sewage Facilities

Air management plays an important and intricate role in the treatment of water and waste.

Wastewater and compressed air

Bacteria -- like any living creature -- need a specific list of environmental conditions and stimuli to survive. This differs from strain to strain, which is why wastewater treatment is so comprehensive; it must eliminate all possible threats from all possible angles to compensate for the billions of possible infectious bacteria that, given time, will self-replicate asexually to form a malignant colony.

While not all bacteria require oxygen, the vast majority of waterborne bacteria is aerobic in nature, and so treatment facilities invest a significant amount of time and energy into air treatment solutions.

Furthermore, a lot of the particularly nasty strains of human contaminate, such as Escherichia Coli, are facultative; they regulate oxygen to live, but under adverse conditions can adapt to anaerobic conditions. Water must therefore go through a number of steps: heating, depriving it of oxygen, chemically treating it, and so on, before it can be recycled cleanly.

As one of the main treatment segments of wastewater treatment and sewage facilities, air treatment can be operating at near full capacity for extensive periods of time. It’s a significant portion of work, and a significant portion of electrical costs for the facility.

Choosing a durable, low-maintenance, and high-performance solution for wastewater treatment impacts not only the continual efficiency of the plant, but the operational costs of the entire operation and your overall energy footprint. Understanding the intricacies, benefits, and specifications of your options makes for a more informed decision on how to best impact your facility’s future.

Compression and blowers

There are three major ways that wastewater treatment facilities routinely maintain their air treatment. These are through the use of air compressors and air blowers.

While we’ll be concentrating on air compressors, it’s important to understand the differences between the respective solutions.

A blower is a (usually) rotary device which simply blows air from the intake to the outtake, and is usually used in areas with low differential pressure. They are high output, but compensate by being low pressure and having a low ability to regulate their pressure.

A compressor compresses air and regulates pressure. They’re used in situations requiring less overall output than a blower (again, usually, and dependant upon model), but can regulate pressure exceedingly well.

Atlas Copco offer ZB and ZS blowers, both of which have Variable Speed Drives (VSD) that are able to alter the energy being used according to the demand on the facility, as wastewater treatment plants often have peak times. This is also important as if a blower is overactive and is blowing too much air into a wastewater tank, this will aerate the water, increasing the chances of pungent odours in the facility.

Understanding costs

As previously mentioned, the cost of constantly running air treatment in a wastewater plant can be exorbitant. Five to ten times the cost of the original purchase price will be spent on energy over the lifetime of the average compressor, which means that energy conservation is key to keeping operational costs down.

Energy costs are so high, in fact, that some estimates place air costs related to energy at up to 70% of the total electrical cost for industrial wastewater treatment plants; a staggering proportion for one machine.

The unspoken cost

There’s another, unspoken cost as to the inefficiency of power in waste treatment. In the USA, it’s estimated that 3% of total energy costs come from powering processing operations in drinking water and wastewater treatment facilities.

Of this, you have the standard economic costs, totaling nearly $3 billion a year and producing 56 billion kWh, but they additionally add around 45 million tons of greenhouse gases into the atmosphere.

This is a catastrophic effect for the ongoing survival of the planet, and yet an important and uninterruptable part of human life. Cities and farmsteads, everywhere that doesn’t have direct access to clean drinking water, needs a way to purify it to stop ourselves going back to mass choleric outbreaks and worse.

The only solution is to continue working at continually decreasing the amount of C02 in the atmosphere, which can be best done by working increasingly on the efficiency of equipment output. Given the proportionately high percentage of cost that air treatment taxes upon a treatment facility, and given the huge output in terms of pollution that they bring, there’s a strongly tied ethical, economic, and environmental incentive to invest in efficient and ethical solutions for your needs.

An energy cost for electricity is an energy cost for emissions, and likewise energy savings. Efficiency in your facility will help both your costs and the world around you.

Atlas Copco believe strongly in the future of the planet, which is why our blowers don’t use oil, and we’re committed to energy efficiency. We meet and surpass all ISO 8573-1 Class 0 (2010) standards, which means zero risk of contamination with pure, oil-free air.

Air compressors, KPIs, and operational usage

Differentiation between air compressors can be most commonly traced to how they perform in four key areas: overall energy conversion efficiency, ease and ongoing cost of maintenance, noise and vibration levels, and in their ability to monitor and report their own readings and efficiency levels.

While only the first seems outwardly and immediately important, each of the others is a key performance indicator of their work that will ricochet throughout other ongoing costs in either a positive or negative manner. Purchase an air compressor with great soundproofing and low vibration and you might find yourself saving on third party soundproofing costs, or an easily maintained one may increase overall worker efficiency and streamline maintenance processes.

Noise and vibration

Noise is a facet of floor placement and friction, and in sufficient amounts can be more than a hindrance; it can be dangerous and impact your worker’s hearing (necessitating steps against it for OHS purposes).

Atlas Copco’s range has a variety of low noise options, which go as low as 63 dB(a), nestled snugly in the lower range between an average human conversation and the regular noise one would put a radio or television. This is achieved through their integrated system within a sound-insulated canopy, removing architectural need for a separate compressor room entirely.

Cost and ease of maintenance

Air compressors are a vitally important part of waste treatment, and a primary useage tool and facility. Any downtime for air compressors affects the entire line; water cannot progress through without it, and the entire operation slows to a crawl.

Maintenance can be expensive, particularly if you don’t have the personnel trained in maintaining those facilities. If not, you’ll have to shell out for costly repairs and technicians every time there’s an issue in the line, stopping all production while you do so until you can call up, hire, and have a technician come out.

In the case where you have trained maintenance staff on hand in the event of a breakdown, you’ll still have to have them sort out the issue at hand, source parts or repair them, and wait out the downtime accordingly.

Ultimately, it’s a question of utmost importance on ease and cost of maintenance, due to the sheer importance of the facility at hand.

As an added bonus, maintenance can jump up operational costs by a significant amount in another way. Up to 30% of air demand can be attributed to leaks and failures, and annual maintenance costs of an average rig can be around 10% of the cost price of the machine.

At Atlas Copco, we believe that regular servicing is key to ensuring reliable operation and a long service life. Our tailor made service for your air compressor products can optimise your investment and maximise your productivity. Our quality genuine parts, highly trained technicians and energy-efficient processes and facilities reduce your cost of ownership throughout the lifecycle of your equipment.

Reporting and analysis

Finally, modern air compressors are run with a variety of self-analytical tools to indicate their overall performance, and in some cases act as a contingency against certain failure states.

Atlas Copco uses an Elektronikon® model control system, which is responsible for maintaining and regulating the main drive motor and regulating system pressure (within a predefined and narrow pressure band). This allows after-the-fact reporting, as well as real-time monitoring of the current output and controls of the air compressor.

Honourable mention for ease of installation

While this is a one-time cost, and the purchase price and maintenance price will over time far exceed it, (lack of) ease of installation can sometimes be a key negative factor in choosing some products.

The reason that this in itself is a KPI is because it’s closely tied to other performance factors. The obvious example might be a bulky model that takes up too much room and is unwieldy to transport into its final destination, but there are subtler ways that it can affect performance.

Chiefly, this has to do with noise and vibration. Inadequate shielding or lack of noise dampening supplied with the compressor can necessitate architectural accommodation in the form of entire rooms for compressors alone. An efficient, noise-dampening model will ensure not just a good fit for installation, but one that doesn’t require additional work around it.

Talk to Atlas Copco to discuss the blower options for your facility, and start operating at your highest efficiency today.

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