Lift Station Maintenance Applications

Applications

Meeting Green Challenges through Automating Lift Station Clean-out

Defining GreenTechnology ……….

The US Environmental Protection Agency (EPA) provides a definition of “Green” as “sustainable development [that] can foster policies that integrate environmental, economic, and social values in decision making.” From a business perspective, sustainable development favors an approach based on capturing system dynamics, building resilient and adaptive systems, anticipating and managing variability and risk, and earning a profit (www.epa.gov/sustainability/basicinfo.htm).

EcoSeed (www.ecoseed.org), a UK based organization dedicated to providing information, news and reference materials for Green Technology provides this definition “products, equipment, practices and concepts that promote environmental sustainability.” Further, “the field of “green technology” encompasses a continuously evolving group of methods and materials, from techniques for generating energy to non-toxic cleaning products”.

What these definitions have in common is the core concept of sustainability. When examining the sustainability of current practices in wastewater pretreatment the use of human effort, fossil fuel consumption, carbon footprint and chemical usage must be scrutinized.

Green Funding ………

Following the previously cited definition of “Green”, the EPA has designated funding for “Green Projects” directed at State Revolving Funds. These monies are to be distributed as low interest loans for projects that address:

· Green infrastructure

· Energy efficiency

· Decentralized wastewater treatment

This is a window of opportunity open for a limited amount of time. States must spend funds within a 12 month time frame. Therefore, it is urgent that facilities define their projects, and implement their acquisitions promptly.

How Anue Systems Work ……….

All Anue Water Technologies’ (AWT) products are designed to recycle resident wastewater in lift stations back into the well. This process provides multiple benefits resulting in lower lift station maintenance costs as well as pretreatment of wastewater.

Going Green: Recycling, Lower Carbon Footprint,

Saving Energy ……….

AWT systems are “green” technology in that they use an all-mechanical recycling process. These systems do not use chemicals, do not require reclaimed or potable water for wash down, or call for human resources to operate the system.

Implementation of AWT systems provides a substantial opportunity to lower the carbon footprint associated with station maintenance. Many systems employ the use of fossil-fuel burning vacuum trucks for clean-out. These very low mileage vehicles, mostly expelling diesel fumes, must drive to a site, open the wet well, vacuum out material, wash-down the well with processed water and then dump the waste. All of this is done from lift station site to lift station site in a never ending cycle of expense.

By contrast, Anue systems are permanently installed in the lift station. They operate unattended, providing an automated, consistent means for ongoing lift station clean-out of fat, oil and grease as well as biofilm. Thus the unending cycle of truck use is broken. Energy is saved by eliminating the use of polluting fossil fuel, saving processed water and even from elimination of energy consuming traffic obstructions and delays during clean-out.

Accumulation prior Homogenized wastewater

to operation after operation

In sum, Anue systems achieve a greener approach to maintenance as well as a reduction in energy use for clean-out.

Preserving Infrastructure and Equipment Delays

Capital Outlays ……….

The recycling process and return of a fractional amount of effluent to the well creates a controlled surface agitation. This important action prevents the formation and build-up of FOG and biofilm. As previously cited, this breaks the clean-out cycle, but even more it serves to preserve lift station infrastructure and equipment. It is well established that FOG and biofilm build-up enable sulfur-producing bacteria to create undesirable compounds including H2S (hydrogen sulfide) and H2SO4 (sulfuric acid). These compounds attack and degrade both equipment and infrastructure alike. The ongoing action of AWT systems will extend the life of structures and equipment in a wet well delaying capital investment for rehabilitation.

Reducing Risk for Sanitary Sewer Overflows ……….

In times of stretched budgets and even under-staffing, lift station maintenance crews may not have adequate time or personnel resources for timely checks of lift stations. Thus the accumulation of FOG and biofilm can occur unabated. Accumulation of FOG on floats can lead to their malfunction and, if not detected and corrected, sanitary sewer overflows (SSO). AWT systems can keep floats clean of build-up and accumulation of FOG. The automated nature of the AWT systems also takes pressure off of maintenance crews reducing risk of SSO as build-up is prevented and lift station operation is assured.

Initiating Pretreatment Decentralizes Treatment ……….

Recycling of wastewater adds two, important and interrelated actions including oxygenation and homogenization. As a result dissolved oxygen levels are driven up, solids are broken down into smaller particle sizes and both elements are mixed along with resident cultures. This dynamic process serves to promote aerobic activity in the wet well and decentralizes the treatment process.

Depending on how widely the Anue systems are deployed throughout a collection system, it is possible that the collection system can be used as an extension of the wastewater treatment plant (WWTP). The benefits of doing so can mean substantial savings at the WWTP including lower total suspended solids (TSS) and improved dissolved oxygen (DO) levels to the plant. Both of these add up to lower operating costs.

Homogenization of wastewater in the lift station provides a consistent and predictable output from the well. Homogenous output improves exit velocity enabling scouring and lowering the accumulation of FOG in the system. Even more, with the homogenous output, lift station pumps will operate at optimum levels, saving energy and potentially extending pump life.

Return on Investment ………

Implementation of any technology must be economically viable or, in other words, it must demonstrate a Return on Investment (ROI). Measuring ROI costs for clean-out of lift stations will vary depending on the method and resources being used. The cost of cleaning will involve both direct and indirect costs, those associated with the current clean-out practices.

The use of vacuum-type trucks can be costly and is certainly a non-sustainable practice. Most utilities either own or will use third-party services. Capturing costs for the latter (third-party) is relatively straight forward. These costs per wet well can range from a few hundred dollars to a few thousand dollars where the rate per clean-out and the frequency determine these costs. In the simplest analysis, if the installed cost of an Anue system can provide a break-even within 12 months or less the acquisition of an Anue system should be easy to justify. In the second year of usage there is an outstanding financial benefit. For example, if a utility is spending $7,500 to clean out a lift station where each clean-out is $1,500 and the frequency is 6 times per year, then they will reach the break-even point with an Anue system in approximately 10 months assuming the installed cost is $6,500. The first year savings is $1,000. In the second year of operation however, the savings will be $6,000. This assumes that there is one clean-out necessary for floatables. The ROI for the first two years is 207%.

For utility-owned trucks the costs are calculated quite differently versus the third party services. The amortized cost of the truck (at an average purchase price of $300,000) plus the operating costs (fuel, maintenance, insurance) plus the labor to operate them are the “direct” costs. The accounting for these costs is complex and depends on factors such as the useful life of the truck. Conservatively, a municipally owned truck costs no less than $3,500 per month and could conceivably be as much as $8,000 per month. The number of lift stations being cleaned per month absorbs these costs. Here again, can the Anue system at $6,500 installed be more cost effective than a municipally owned vacuum truck? Vacuum trucks are not only used by municipalities for lift station clean-out, but also a variety of similar uses such as storm drains or storm water vaults. Thus, the suggestion that all trucks can and should be eliminated is not being proposed. Instead, the Anue system can conserve expenses in one of two, significant ways. First, with municipalities that own multiple trucks, implementation of the Anue systems could limit the number of trucks needed. For example instead of five trucks, the municipality may only need four trucks. Second, the use of Anue systems could extend the life of existing trucks by limiting their usage.

In both instances though, there remains the question of sustainability. Is the current practice of using these low mileage trucks for a never ending cycle of clean-out a green approach? The obvious answer is no, given the factors that have already been presented herein. It is not sustainable economically. It is not sustainable environmentally. For these two important reasons, municipalities must seek better alternatives.

Conclusion ……….

According to the Water Environment Federation (WEF), all municipalities should be encouraged to contact state revolving fund program managers and inquire about these EPA funds. Clearly, the first step is to recognize alternatives that exist. The Anue systems are providing current uses with a truly green alternative to existing practices. They offer the opportunity to automate an otherwise manual clean-out. They can limit use of chemicals. The Anue systems will provide a rapid return on investment. For these reasons they offer potential users an opportunity to seek out funds that support Green Technology.

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