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Safety in waste water treatment facilities

Safety in waste water treatment facilities

In addition to specific process areas of a waste water treatment facility where a wide range of intrinsically safe solutions are required, the water filtration equipment and the entire waste water treatment plant itself must be monitored to protect against corrosive, dusty, dirty, and explosive atmospheres, in addition to lightning protection and purge suppression. Pepperl+Fuchs has a wide range of protection methods that will keep the waste water treatment plant safe and operating effectively.



Corrosion
Prevention, monitoring, and repair are the main contributors to the costs of corrosion on water filtration equipment.  It does not include downtime costs. These costs are better controlled when corrosion is viewed as a process variable, rather than a purely historical value or in a complex, scientific method. On-line, real-time monitoring with CorrTran® MV allows immediate changes to be made to the waste water treatment process as corrosion occurs thus reducing the effects of corrosion and cowering operating costs for water filtration.


Lightning and surge protection
Sewage treatment plants are especially exposed to the risks of atmospherical discharges and lightning strike. In addition, lightning strike, static electricity and power surges can spread very easily due to the great expanses of networks and multiple grounds that exist in the sewage treatment plant.

There are two phenomena that can occur in the typical industrial sewage treatment plant that are induced by lightning, large electrical equipment, and welding equipment: lightning strike and power surges.

A lightning protection system consists of external protection, and internal lightning protection. External lightning protection minimizes fire risk by lightning strike and the realization of the Lightning Protection Zones Concept helps to optimize the availability of the installation to a maximum level. 

A part of the lightning current flows directly to grounding via the earth-termination system.  The other part flows via the external supply lines of the sewage treatment plant and could damage the installation. These external supply lines must be furnished with lightning current capable surge protective devices (SPDs). Surge arresters reliably protect the terminal equipment in the waste water treatment facility against conducted transient voltage.

Instrumentation in designated areas of the water treatment plant is susceptible to lightning strike or surge. To protect this equipment, water treatment plants install advanced controls using a DCS or PLC system. Damage to the water treatment equipment may result in draining polluted water into the local watersheds, rivers or lakes.  Pepperl+Fuchs offers signal conditioning applications that provide isolation and prevent ground loops, thus protecting the water treatment plant.

Intrinsic safety
Intrinsic safety is used where explosive gases like methane CH4 can collect. Our H-System and K-System isolators together with our RPI Remote I/O System provide the solution. The digestion area of a waste water treatment facility is where microscopic bacteria digest the sludge and break it down into methane gas. These digesters produce so much methane and carbon dioxide CO2, that it can actually be used to provide heat to the digester tank and operate electric generators or motor vehicles. 

Purge
Raw sewage, corrosive chemicals, and sludge in a waste water treatment facility can damage industrial instrumentation and equipment. Pepperl+Fuchs has introduced the new Enviro-Line of pressurization systems (10E-WGS Series). This will purge panels, cabinets, and other equipment from corrosive, dusty, dirty, atmospheres.