Wastewater treatment technologies have come a long way in the past decades but more reliable and efficient treatment technologies continue to be in demand. As a result experts are searching for an all-encompassing solution to enhance the treatment processes.
What happens when Oxygen is used?
All secondary aerobic treatment operations require sufficient transferred oxygen. There are numerous ways that using pure oxygen can help to guarantee that the system is operating properly and that the required oxygen level is maintained with minimal negative consequences.
The loading oxygen demand (BOD/COD) at the treatment plant frequently changes as production rates, flows, product standards, and other factors change. Wastewater systems are frequently inadequately sized to cope with these changes. Another area where pure oxygen might help is in the respiratory system.
Oxygen can help with a variety of other issues that arise in secondary treatment systems.
For example, dead zones - areas with no or little dissolved oxygen as a result of poor mixing or malfunctioning equipment - can be remedied by injecting oxygen into specific locations.
In most situations, oxygen is delivered to the treatment area via separate ways, allowing it to be used on an, as-needed basis, and operated independently. This gives you the freedom to suit your plant's needs while lowering your chemical usage and operational costs.
Air can remove hydrogen sulphide and/or VOCs (volatile organic chemicals such as benzene, toluene, or methanol) from wastewater during the aeration process. Pure oxygen often achieves a higher level of dissolved oxygen than traditional compressed air methods. Because pure oxygen is often transmitted at a high rate (70-90 percent) and there is no nitrogen to interfere, it can result in enhanced mass transfer. These variables help to reduce the risk for stripping, which is common in air-based systems with VOCs. Even low dosages of oxygen used prior to secondary treatment can sometimes assist maintain system health by ensuring adequate dissolved O2, which prevents filamentous and other undesirable bacteria from forming.Healthy bacteria result from adequate oxygen levels, which leads to increased treatment capacities.
How does pure Oxygen improve Wastewater Treatment?
The highest level of dissolved oxygen is achieved when pure oxygen is used. When using pure oxygen to improve the air system in secondary treatment, there are various potential benefits:
• Improved sludge settling
• Reduced smells
• Loading (BOD/oxygen demand) increases
• Lower levels of volatile organic compounds (VOCs)
• Possibility of bettering ammonia treatment
• Increased system operation flexibility (blower turndown, etc.)
• Capacity to fulfil high production/peak demand
• Assist in meeting permit requirements (e.g., NPDES)
• Assist in emergency situations (i.e., aerator failure)
• Keeping the system in good shape (sufficient dissolved oxygen in pipelines, final dissolved oxygen)
• Permit requirements can be accomplished without requiring major plant changes.
Year after year, this may be the most cost-effective method of achieving goals such as satisfying permit limitations, allowing higher production, cutting costs, and avoiding capital expenditure.
How to calculate the oxygen requirement in WWTP?
The aerobic heterotrophic microorganisms included in the activated sludge process utilize oxygen as an electron acceptor in their energy metabolism. In the activated sludge process, oxygen is necessary for oxidation of the influent organic matter, cell development, and endogenous respiration of the microorganisms. The aeration equipment must be able to maintain a dissolved oxygen level in the aeration basin of around 2 mg/L while mixing the solid and liquid phases thoroughly. Knowing the ultimate BOD of the wastewater and the amount of biomass discarded from the system each day can be used to predict the oxygen requirement for an activated sludge system.
If all of the substrate extracted by microbes is completely oxidized for energy purposes, the total oxygen content will be calculated as:
Total O2 requirement (g/d) = Q(S0-S)/f
Where, f = ratio of BOD-5 to ultimate BOD
However, all of the oxidized substrate is not utilized for energy. A fraction of the substrate is used in the biomass synthesis process. There is no accumulation of biomass because the system is believed to be in steady state, and the amount of biomass generated is equal to the amount of biomass lost.
As a result, the corresponding amount of substrate converted to new biomass is not oxidized in the system, and no oxygen demand is created. The amount of oxygen required to oxidize one unit of biomass is 1.42 units.
30 to 55 m3/kg of BOD eliminated is the typical air demand for conventional ASP. BOD is eliminated at a rate of 24 to 36 m3/kg with fine air bubble diffusers. The air required for extended aeration ASP is higher, on the range of 75 to 115 m3/kg of BOD eliminated. When constructing aeration equipment to handle peak demand, a safety factor of 2 should be employed.
What can Netsol Water do to assist?
When determining the demand for pure oxygen in a wastewater treatment plant, speaking with a trustworthy provider who can ensure a consistent supply of high-purity oxygen is a great place to start. Wastewater treatment operations will be streamlined with a consistent supply and a top-notch specialist to guarantee that quality requirements are met, equipment is running properly, and costs are kept in check. It's critical to investigate and understand all choices in the wastewater treatment area, since technology can help a plant run more efficiently for years to come.