Too much air how to make money fast ways understanding the critical… treatment plant operator

Over-aeration can also cause operational problems. Operators love a mixed liquor that settles well. This happens when the microorganisms in the aeration tank excrete how to make money fast ways a sticky film around their cells as their food gets how to make money fast ways depleted. Aeration keeps the bugs in suspension, allowing them to collide and ultimately stick together, forming a floc. The floc exhibits a snowball effect: by the time it reaches the secondary clarifier, it is denser than water and settles. Over-aeration can break this floc apart, causing pin floc or small, dispersed floc that does not settle well.

Anoxic zones used for denitrification can also turn partially aerobic, or oxic, due to the high DO in the internal (nitrate) recycle flow. In a biological nutrient removal facility, internal recycle flow can be 400 percent or more of how to make money fast ways the influent flow. This recycle flow pulls liquid that is high in nitrates how to make money fast ways from the end of the aerobic zone, then discharges it back to the head of the anoxic how to make money fast ways zone, where there should be very little or no DO.

Operators rely on denitrification not only for nitrogen removal, but also for the alkalinity that is released in the how to make money fast ways denitrification process. If denitrification is inhibited, the operator may have to add chemicals to keep the how to make money fast ways alkalinity and ph in check. Alkalinity is so important that many operators add a denitrification how to make money fast ways step even if it’s not needed for nitrogen removal, just to bring back some free alkalinity and oxygen to how to make money fast ways the system and save money on chemicals.

Another myth is that the mixed liquor suspended solids (MLSS) will not re-suspend if the aeration system is shut down. All scenarios are case-specific, but many facilities can re-suspend the solids even if the air has been off how to make money fast ways for an hour or so. In general, the required DO for solids processing is 0.5 mg/L in the floc and 2.0 mg/L in the mixed liquor.

Probably the easiest way to monitor DO is with a how to make money fast ways hand-held meter with a data logging function. Set the probe in the mixed liquor for as long how to make money fast ways as the data logger will collect data (one reading per half hour, 48 readings per day as a starting point). Plot the DO for a week or so on a how to make money fast ways chart. If the DO is over or under your ideal setpoint, reprogram the controls to increase or decrease aeration, or even turn off the aeration at a high DO how to make money fast ways setpoint for a certain period. Where you put the probe in the aeration tank matters. Think about the ideal setpoint for the location you are how to make money fast ways measuring to get the desired treatment. Also, ask your consulting engineer what your DO setpoints should be.

The operator of the hamilton township wastewater treatment plant in how to make money fast ways ludlow, pennsylvania, applied knowledge gained from an energy efficiency training conducted by how to make money fast ways the U.S. EPA region 3 and the pennsylvania department of environmental protection. The plant’s 0.07 mgd activated sludge process includes ammonia removal. The operator chose to cut DO from 6-9 mg/L to 2 mg/L.

Optimization was more complex for this 7.1 mgd plant in pennsylvania, which also has an activated sludge process with ammonia removal. During the warm summer months, the aeration tank detention time was more than enough to how to make money fast ways achieve ammonia compliance. The operations manager knew that if he could denitrify at how to make money fast ways the front end of the aeration tank by closing some how to make money fast ways air-supply valves, he would bring back alkalinity, reducing chemical costs and saving energy.

The aeration system consisted of a multistage centrifugal blower with how to make money fast ways an automated inlet valve controlled by the header pressure. By closing the aeration drop leg ball valves to about how to make money fast ways 90 percent (to allow some air for mixing) in the first third of the tank, a successful anoxic zone was created. Closing off one-third of the diffusers raised the air header pressure, thus automatically closing the blower inlet valve somewhat to keep how to make money fast ways the header pressure constant. A partially closed inlet valve admits less air, reducing energy required by the blower.

A power logger installed on the blower during the cold how to make money fast ways season (100 percent aerated tank) and warm season (66 percent aerated, 34 percent anoxic tank) recorded the savings. Energy use was cut almost in half, saving about $5,000 per month. To achieve further savings, the plant is investing $100,000 to upgrade its aeration system and controls to automated how to make money fast ways DO control and “most open valve” control technology.

Aerobic digesters often accumulate a large amount of nitrate. As the bugs consume each other (endogenous respiration), there is a release of nitrogen compounds. These compounds are oxidized, nitrate is formed and acid is released (alkalinity consumed). This represents another opportunity for on/off aeration to reduce the nitrate and maintain alkalinity levels.

This agency in pennsylvania upgraded from conventional secondary treatment to how to make money fast ways a four-stage bardenpho process with chemical phosphorus removal and denitrification filters. The digester decant levels for nitrate-nitrogen (NO3-N) during summer 2014 were over 80 mg/L. The operator experimented with on/off instead of continuous aeration, setting the blowers to run two hours on and two how to make money fast ways hours off. This reduced the NO3-N discharged back to the main process to 0.18 mg/L, saving 54,000 kw ($4,300) per year. Added benefits are a reduction in concentrated nitrate in the how to make money fast ways supernatant and the restoration of alkalinity to the system.

In 2008, the borough replaced the aerobic digester coarse-bubble diffusers with fine-bubble diffusers. By cutting the need for two 250 hp blowers in how to make money fast ways half, the plant saved $72,000 per year and achieved payback in four months. In 2010, new positive displacement blowers with variable-frequency drive controls were installed in the aerobic digester. The more efficient blowers supply air at lower horsepower. The added aeration capacity enabled the plant to haul in how to make money fast ways more waste and increase revenue. Net savings are $36,000 per year.

The latest investment was a $200 timer for the activated sludge blower. The plant electrician wired the timer and set the “on” cycle for four hours and the “off” cycle for four hours, reducing energy usage by half. This enabled the creation of an anoxic environment for denitrification. The change saved $10,000 per year on energy and $50,000 per year by eliminating lime and soda ash addition how to make money fast ways for ph and alkalinity adjustment. To top it off, mixed liquor settling characteristics improved.

With any process change, it is necessary to involve the plant staff, the regulatory agency and the consulting engineer. It is best to make small, incremental changes and wait for the results. It is important to collect data, including DO levels, ORP readings and alkalinity concentrations to be sure you’re on track. When aiming for low to no DO in anoxic zones, low-DO filaments could begin to thrive, slowing down settling. Changes require frequent monitoring.

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