Each year, operators, engineers, manufacturer representatives and more, come together at the Indiana Water Environment Association's (IWEA) Annual Conference to discuss the latest in the world of water, wastewater and stormwater. It provides an opportunity not only to learn, but also to share experiences with others in the water field. Since, it is impossible to catch all of the presentations, we have summarized some of the topics that Wessler’s engineers presented on for you.
1. The Mystery of Anoxic and Anaerobic Treatment - Katie Jackson
Most wastewater treatment plants (WWTPs) currently have a phosphorus limit of at least 1 mg/L and ammonia limits. In the future, phosphorus limits will be lower and it is likely that a total nitrogen limit will be added. Since it is very costly to treat phosphorus to a low limit with just chemicals, and chemicals cannot help reduce nitrogen in a system, biological treatment options must be considered. In order to reduce phosphorus biologically, anaerobic conditions are required. Anaerobic means that there is a total absence of oxygen. In order to remove nitrogen via denitrification, anoxic conditions are required. Anoxic means there is no free oxygen, but oxygen is found in compounds such as nitrites and nitrates. One way to verify that conditions are correct for the type of treatment required, is to use oxidation reduction potential (ORP) probes. There are a number of different biological process configurations that can remove phosphorus, nitrogen or both. Each process has pros and cons, which should be considered when trying to determine which process is best for your plant.
2. Using SBRs in Large and Small Scale Applications - Kwabena Adu-Sarkodie
Series batch reactors (SBRs) are an excellent alternative to continuous flow processes, particularly when a WWTP is limited on space. SBRs can even be used for biological nitrogen and phosphorus removal. There are four main phases in the SBR process, which all occur within the same tank: fill, react, settle, decant. If nitrogen removal is desired, the fill stage can be broken down into two parts, one where the tank is just being filled, and the other where the tank is filled and mixed. This second part of the filling phase creates the anoxic conditions required for denitrification. Another advantage of SBRs is that they can be used for both large and small WWTPs. One difference that can be seen between large and small scale SBRs is whether or not blowers are needed. In small scale applications, blowers are often not required - as a mixer/aeration/decanting system can be used instead.
3. Energy Savings at the WWTP - Bridget Philpott
In many cases, 25-35% of a WWTP’s total spending is on their energy bill. In order to reduce the energy bill, it is important to think about how electrical consumption can be decreased, as well as ways to reduce the plant’s peak demand. Large scale modifications, such as process changes and purchasing new equipment, can be an effective way to reduce energy. However, these types of changes can be costly and are not for every plant. An alternative approach is to make operational modifications to your existing system. Operation changes that can help a plant reduce their electrical consumption, include: adding variable frequency drives, using online analyzers and incorporating denitrification into your process. Operation changes that can help limit a plant’s peak demand include: dewatering and thickening during periods of low flow, staggering pump and blower run times, and slowing the ramp up speed of variable frequency drives. Overall, operational modifications are low cost and can result in manger savings.
If you have questions about any of Wessler’s presentations, or other topics covered at the IWEA Annual Conference, feel free to contact us!
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