Wastewater Treatment

Wastewater is used water that has been adversely affected in quality by substances like human waste, food scraps, oils, and chemicals. Wastewater treatment, also known as sewage treatment, is the process of removing contaminants from wastewater through physical, chemical, and biological procedures. Wastewater treatment facilities clean used water for the benefit of our environment and personal health. However, the treatment process is chemically intensive and can pose a threat to the safety of personnel working at the facility. Consequently, the wastewater treatment facility manager must ensure that the facility's safety is not compromised by instrumenting the plant with a comprehensive gas detection, alarming, and mitigation system.

Gas Detection and Alarming

The process of treating wastewater requires a plant to utilize many toxic and dangerous gases, which also causes the production of other toxic and combustible gases. Moreover, there are many enclosed spaces in a wastewater treatment plant where toxic gases can build up, or non-toxic gases can deplete oxygen to endanger plant personnel. To ensure maximum wastewater treatment safety, these hazardous gases must be accounted for:

  • Combustible Gases
    • Methane (CH4)
    • Pentane (C5H12)
    • Hydrogen (H2)
  • Hydrogen Sulfide (H2S)
  • Oxygen (O2) Deficiency
  • Carbon Monoxide (CO)
  • Chlorine (Cl2)
  • Sulfur Dioxide (SO2)

Processes within a wastewater treatment facility include pumping and lifting stations, influent screening, sludge processing, digestion, and final disinfection. Different processes within a wastewater treatment facility require different gas sensors. Areas with potential hazardous levels of gases include:

  • Pumping station and wet well – Combustible Gases, Oxygen Deficiency, Hydrogen Sulfide
  • Influent and barscreen room – Combustible Gases, Hydrogen Sulfide, Oxygen Deficiency
  • Barscreen and conveyor room – Combustible Gases, Hydrogen Sulfide
  • Barscreen container and grit screen room – Combustible Gases, Hydrogen
  • Primary Clarifier – Combustible Gases, Oxygen Deficiency, Hydrogen Sulfide
  • Primary wet wall – Combustible Gases, Oxygen Deficiency, Hydrogen Sulfide
  • Grit chamber and wet wall – Combustible Gases, Oxygen Deficiency, Hydrogen Sulfide
  • Sludge treatment – Combustible Gases, Oxygen Deficiency, Hydrogen Sulfide
  • Sludge incineration – Carbon Monoxide
  • Basement-generator area – Combustible Gases
  • Digester-basement – Combustible Gases, Hydrogen Sulfide
  • Digester-first floor – Combustible Gases, Hydrogen Sulfide
  • Odor removal equipment – Chlorine, Hydrogen Sulfide, Ammonia
  • Furnace room – Combustible Gases, Carbon Monoxide
  • Filtration room – Chlorine, Hydrogen Sulfide
  • Final disinfection – Chlorine, Ammonia, Sulfur Dioxide

Automation and Integration Strategies

Detecting hazardous gases and issuing alarms are important steps, but it is equally important to take remediation actions. This can be done through integrating the gas detection and alarm system with the Supervisory Control and Data Acquisition (SCADA), the Programmable Logic Controller (PLC) or the Building Management System (BMS) responsible for automating the larger facility. For example, a common integration would be a Modbus RTU gas sensor with a BACnet/IP BMS. Other automation processes may include providing notifications as a local alarm to an employee's phone, tablet, and/or PC.

As these systems are automated, the regulatory agencies require that the systems be “performance approved" and checked on a periodic basis.

Products for Wastewater Treatment

Wastewater treatment facilities require a gas detection system that includes gas detection modules, a method to communicate to a controller, flexible alarm handling, and a method for communicating data to higher-level systems to take facility-wide remediation actions. The ability to collect large amounts of data for subsequent analysis is also key. 

Sierra Monitor's Nationally Recognized Testing Lab (NRTL) approved Sentry IT fire and gas solutions can ensure the safety and protection of assets and personnel in wastewater treatment facilities. Sierra Monitor's detectors and controllers offer the industry's best Return on Investment (ROI) to the facility manager through innovations that minimize installation, commissioning, calibration, and life cycle maintenance costs. Sierra Monitor's Sentry IT solution is the preferred choice for the diligent and ROI-oriented facility management professional.

Gas Detectors:

Fire Detectors:

Fire and Gas Detection Controllers:

Unlike most fire and gas vendors, we also include our leading FieldServer multi-protocol gateways to connect our Sentry IT system to the facility’s SCADA system, or PLC, or BAS, and to the cloud for remote monitoring, control, and big data analytics.

FieldServer Gateways: