Abstract

The study presented here is a preliminary effort to compare sewer operational and maintenance techniques to assess their efficiency in optimizing the amount of gases (that is, H₂S and O₂) in sewage collection networks in Mashhad-Iran. Field tests were carried out using high-pressure water jet cleaning (HPWJC), portable blower ventilation (PBV), and water flushing (WF) techniques at specific intervals. The outcomes revealed that proactive maintenance is useful to optimize the range of gases in sewers; that is, H₂S < 1 ppm and O₂ > 20%. The results obtained from performing the designed methods showed that test No.2 (2 times/30 days), test No.6 (3 times/30 days), and test No.8 (2 times/30 days) for HPWJC, PBV, and WF techniques respectively are efficient enough to satisfy H₂S and O₂ ranges at headspace of the networks. However, among these, WF technique with the application of 2 times/30 days was nominated as the most effective method due to its safety to the network and its performance in leading the H₂S amount to less than 1 ppm and O₂ percentage by more than 20%.

Key words: High-pressure water jet cleaning, hydrogen sulfide, oxygen, portable blower ventilation, sewage network management, sewer gas, water flushing.