Wastewater Operations

Wastewater Operations Branch (WWO) is responsible for conveying, collecting and treating wastewater (sewage).

With a staff of about 700 employees, WWO is responsible for the operation and maintenance of 40 wastewater treatment plants (WWTPs), three (3) wet weather facilities, a collection system with over 380 lift stations and over 6,100 miles of pipelines, ranging in size from 2 to 144 inches in diameter located throughout the Houston area.

The Collection Systems Analysis Section, Technical Services and Operations and Maintenance oversee the implementation of the Collection System Pipe Renewal Program. The Construction Management Group monitors construction quality and progress of sewer rehabilitation and emergency repair projects, while the Contract Management Section is responsible for the development, renewal, administration and management of service contracts

Domestic Sewage Treatment Process 101

Domestic sewage is collected and transported via pipes and lift stations to Wastewater Treatment Plants.

Once raw sewage arrives at the WWTP:

  • It is pumped through bar screens to remove large particles and then goes through the grit removal system to remove sand and silt. Screened sand and silt are disposed of at the municipal landfill.
  • Sewage proceeds to be treated in a reactor to separate impurities using air/oxygen, which is an activated sludge process, a biological process by which microorganisms are used to remove impurities from sewage.
  • It then flows to a clarifier, where solids are separated from the liquid stream. 
  • Solids settle at the bottom of the clarifier and are withdrawn and returned to the reactor to treat incoming sewage
  • Clear water then overflows into the chlorine contact chamber, where it is disinfected by using sodium hypochlorite as a source of chlorine to destroy the pathogens.
  • Prior to discharging into the receiving streams (bayous)
  • Chlorine is removed by adding sodium bisulfate.
  • Excess microorganisms, called biomass or excess sludge, are removed from the process for further treatment and are turned into fertilizer

Additional Information

Protect Our Pipes

70% of sewer overflows in Houston are caused by clogs from fats, oils and grease poured down the drain and wipes flushed down toilets.