How to remove heavy metals from Power plants?
Key effluent regulations for power plants include flue gas desulfurization (FGD), effluent restriction guidelines (ELG) and coal combustion residue restriction (CCR).
Coal operators are looking for solutions to eliminate the heavy metals found in both scenarios. The “EPA 2015ELG regulation” regulates the emission of ash transport water and sets a limit on the concentration of toxic heavy metals that can be emitted from the FGD system of steam power plants. The proposed regulation has recently been updated.
The need for heavy metal removal in power plant drainage is required for almost all FGD systems.
All FGD wastewater systems require solutions for removing heavy metals within the limits established by the EPA based on physicochemical biological treatment systems.
In addition, due to CCR constraints, coal-fired power plants need to consider ways to eliminate coal ash ponds and minimize the use of process water in the treatment of CCR and wet FGD systems.
These utilities will be one step ahead by looking for options to address this ever-changing regulatory environment and proactively finding solutions that work on their sites.
An effective treatment to consider is a physicochemical biological solution for removing heavy metals in coal-fired waste streams, coal ash ponds, and FGD systems.
For coal ash ponds, these systems may include reaction tanks, purification equipment, and pressure filters. FGD system solutions include mixing tanks, purification equipment, ultra filtration and continuous back flush filters.
The ideal solution adapts to a variety of unique site conditions. Solutions can start with a standardized approach, but utilities need to work with solution providers who can adapt and modify existing therapies to meet the unique needs of the site. Physicochemical solutions are adopted to eliminate heavy metal pollution and protect the groundwater in the area.
If a plant sought to remove heavy metals, TSS, and nitrates from FGD wastewater for discharge at ELG levels, their problem was solved with a treatment system that included chemical addition, sedimentation, medium filtration, and selenium treatment.
A strategic approach followed
The energy industry is uncertain about the impact of CCR and ELG compliance requirements and timing. The utility makes a decision on future heavy metal waste stream management methods based on ELG and CCR rules in the context of pending revisions where regulatory graphs show arsenic removal over time at drainage levels below limits.
The removal of arsenic and the removal of additional solids can be done with a horizontal pressure filter, which consists of several cells and allowed self-generated backwash.
Netsol can support and control the automation of each process step, data logging, and the addition of chemicals. This process also enables a biological system for selenium removal.
But there are still more challenges to face!
For example different and changing discharge regulations may apply in the future, even in states where no formal policies have been implemented to date. While these regulations encourage utilities to change, cost-benefit analysis can identify treatment technologies that meet future regulations while providing future benefits such as: Improved boiler efficiency and improved water reuse.
We need to consider a solution that not only achieves heavy metal removal, but also addresses the economic impact on utilities in areas such as operations and cash flow. If the size of the plant, the quality of the inflow and the geographical conditions are different, one way to ensure the best solution is to customize it. The utility must be able to work with the solution provider as a trusted partner. Such partnerships ensure that the most effective methods are used to meet future EPA regulations, from design to operation. We at Netsol water are ready to help with that.