The city of Black River Falls in Wisconsin used chemical treatment with ferric chloride (FeCl3) to achieve their effluent total phosphorus (TP) permit of 1.0 mg/l. Historically, the chemical dosing rate was manually adjusted on a daily basis based on the measured effluent TP concentration. The plant was upgraded with an OSCAR process performance optimizer control system with phosphorus controller, which uses continuous measurement of orthophosphate. Read the full case study to learn more.
Storey County, NV, just southeast of Reno, needed to replace an outdated wastewater treatment plant that serves the historic communities of Virginia City and Gold Hill. The new site was on the side of a hill, presenting challenges for the design of the plant and the orientation of its processes. Also, the new plant area was entirely within a district on the National Register of Historic Places. Read the full case study to learn how the new modular design allows for an efficient wastewater treatment solution.
The overall wastewater treatment process is complex, and each step is integral to ensuring water is properly purified. Effluent ends up in the plants, containing substances that must be removed before the water can be properly cleaned and returned for use. The range of potential contaminants is almost endless, and can include food, pulp, waste, or other substances. Afterwards, the water requires further scrubbing, with the aid of bacteria. It is in this part of the process that compressed air (ideally provided by energy-efficient rotary lobe blowers) plays a vital role.
The Escalon Industrial Waste Water Treatment Facility’s service area is seasonal and centered on tomato and pickle processing. The production season (roughly mid-July through mid-October) sees high hydraulic- and BOD loads that strain the facility’s capacity. During the high season highly variable BOD load depletes DO and causes permit violations and odor complaints. Praxair installed 4 X 15 HP Medium Velocity Oxygenation (MVO™ oxygenation system), with the ability to deliver up to 6 TPD of oxygen to supplement the existing aeration capacity at the facility.
A modern, master-planned community in the Texas Hill Country needed an affordable wastewater collection and treatment system that could be installed in phases and would perform as reliably as a large municipal system but without the cost, odor, or need for a full-time operator.
The Hagerstown Wastewater Treatment Plant in Maryland incorporated several plant modifications, one of which was the conversion of their disinfection process from the use of ozone to UV.
A leading fruit juice company had expanded over the past ten years and increased wastewater flow from 7,000 to 11,000 gallons per day (gpd), without upgrading its wastewater treatment plant.
The LeSourdsville WWTP in Butler County, Ohio, was required to meet their NPDES permit requirement of 6 mg/l dissolved oxygen at the plants Miami River outfall.
A common first step in the secondary treatment process is to send wastewater to an aeration tank. In an aeration tank, bacterium is used to effectively break down pollutants into less harmful components. Wastewater aeration provides the appropriate oxygen level so that aerobic bacteria can thrive in degrading pollutants such as iron and manganese as part of the wastewater treatment process. Aeration can also be used to destroy anaerobic bacteria that perish in the presence of oxygen. Aerobes that can break down pollutants 10-100 times faster than anaerobes are used most frequently.
Aeration is also used to improve waste lagoons and other waterways such as lakes and reservoirs where oxygen deficiency contributes to taste, odor and pollutant problems. Equipment used for wastewater aeration includes low cascades, jet fountains, spray nozzles, blowers, submerged perforated pipe and porous plates or tubes. Whether the water is thrown into the air via a fountain or diffused by air bubbles being blown or drawn into the wastewater in an aeration tank, aeration works by increasing the area of contact between the oxygen in the air and water.
The most common wastewater aeration process in use today is the air diffusion process, where air is introduced from blowers through diffusion tubes suspended in a spiral flow tank, or in some cases, through diffuser plates in the bottom of the aeration tanks.