Use of Air Circulation Pipes in Deep Dropshafts for Reducing Air Induction into Sanitary Sewers

Zhang, Wenming; Zhu, David Z.; Rajaratnam, N.; Edwini-Bonsu, Stephen; Fiala, Jan; Pelz, W.

doi:10.1061/(asce)ee.1943-7870.0001046

Cited by 27 publications

(5 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To determine the ventilation locations and air extraction rates, the fundamental physics of air movement in sewer networks must be understood [56]. The authors of [51] mentioned that Pescod and Price (1978) were perhaps the first to present scientific experimental studies on air movement in sewer systems.…”

Section: Air Pressure Transient and Ventilation In Sewer Systemsmentioning

confidence: 99%

“…Dropshafts can entrain a large amount of air and pressurise the air space of downstream sewers, leading to odour complaints when odour escapes from the sewer system [56]. Due to the difficulty in obtaining field measurements, the flow in dropshafts has been studied quite extensively in laboratories focusing on hydraulics of water flow [61] and air entrainment [62].…”

Section: Hydraulic Structure Dropshaftsmentioning

confidence: 99%

“…The authors of [61] measured air induction rates of dropshafts with two drop heights (7.7 and 6.3 m) in different water flow conditions and found that a larger drop height resulted in a higher air demand. In addition, A research [56] found that using a retrofitted dropshaft (air circulation pipe) could result in reducing the downstream pressure by about 40-50% compared to that before the retrofitting. Furthermore, a laboratory study in Canada showed that the pressurisation inside the dropshaft could be reduced by up to 26% at large water flow rates, while a field monitoring result showed that the air pressure in the upstream/downstream manholes and the airshaft varied in response to the variation of the sewage flow rate.…”

Section: Hydraulic Structure Dropshaftsmentioning

confidence: 99%

See 2 more Smart Citations

Integrating the Design of Tall Building, Wastewater Drainage Systems into the Public Sewer Network: A Review of the Current State of the Art

Sharif¹,

Gormley²

2021

Water

View full text Add to dashboard Cite

The design of above ground building drainage systems follows codes and standards that only give cursory recognition to the fact that this system connects, in the majority of cases, directly to a vast network of sewer pipes leading to a wastewater treatment plant. At the same time, for underground systems, airflow within as well as in and out of sewers is often neglected during the design of sewers, which depend on these building installed systems for pressure relief and venting. There is clearly an interaction between the two systems, yet this is not reflected in the design guidance, particularly inside buildings where air pressure fluctuations can lead to the destruction of water trap seals and the ingress of foul air containing sewer gases and potentially harmful pathogens. In this systematic review of historical research and design practice for both above and belowground drainage systems, we present the current state of the art and make recommendations for advancements that recognise the interaction between systems and present a view on how design could be advanced in a more holistic way.

show abstract

Section: Air Pressure Transient and Ventilation In Sewer Systemsmentioning

confidence: 99%

Section: Hydraulic Structure Dropshaftsmentioning

confidence: 99%

Section: Hydraulic Structure Dropshaftsmentioning

confidence: 99%

See 1 more Smart Citation

Integrating the Design of Tall Building, Wastewater Drainage Systems into the Public Sewer Network: A Review of the Current State of the Art

Sharif¹,

Gormley²

2021

Water

View full text Add to dashboard Cite

show abstract

“…Many studies have been carried out on the air entrainment in plunge dropshafts (Anderson & Dahlin 1975;Ervine & Falvey 1987;Chanson 2007;Granata et al 2015;Granata 2016;Ma et al 2018;Granata & Di Nunno 2022). The relative air demand, denoted by the ratio of the entrained air flow rate to the water flow rate (Ma et al 2016), was different in different structures: about 1.4 in a dropshaft of 3 m high (Rajaratnam et al 1997), about 40 in a dropshaft of 8 m high (Camino et al 2015) and about 160 in a prototype dropshaft of 25 m high (Zhang et al 2016). The air demand increases as the plunge dropshaft increases (Camino et al 2015).…”

Section: Introductionmentioning

confidence: 99%

Investigation on water and air characteristics in Helicoidal Ramp Dropshafts

Zhang

Liu

2022

Water Science and Technology

View full text Add to dashboard Cite

Plunge dropshafts are widely used in urban drainage systems, but they can carry large amounts of air into the system, endangering the safety of the system. In this paper, a 3D numerical model is established to investigate the water flow configuration and air characteristics in a helicoidal ramp dropshaft. The simulations under different outlet pressures and water flow rates were simulated, and the results show that the air demand decreases with the increase of outlet pressure, especially in the case of low water flow. In the case of higher outlet pressure, the air demand first increases then decreases with the increase of the water flow rate. The dragging force of water has little effect on the pressure gradient in the dropshaft. The increase of ramp turns leads to the increase of terminal velocity at the same flow rate, and the air demand first increases and then decreases with the increase of ramp turns.

show abstract

“…Previous studies provided valuable information on ventilation systems (Jack et al 2006). Municipalities, such as Edmonton and Los Angeles, have used forced ventilation, where sewer air is extracted with fans or blowers and is routed to air treatment facilities (Zhang et al 2015). Ventilation equipment must be properly sized, and ventilation should always be maintained while the structure is accessible (Wierzchowski et al 2009).…”

Section: Introductionmentioning

confidence: 99%

Enhancing the ventilation of sewers by using inhaled air in the vertical stack of a building

Jin

Zhang

2018

Water Practice and Technology

View full text Add to dashboard Cite

Improving the ventilation of sewers could control the production of hydrogen sulfide (H2S) and methane (CH4), which are associated with anaerobic conditions. In this manuscript, a ventilation method using inhaled air from the drainage of the vertical stack of a building was proposed, and a model based on the dimensional method was established to calculate the airflow rate of the inhaled air. By observing the air pressure and air velocity of the ventilation cowl and the opening hole of the sewers, it was found that the inhaled air flowed down with water and that approximately 94% of the inhaled air would flow into the headspace of the sewer to enhance ventilation. According to the model and the observed service condition of toilets in the building, the daily average quantity of the air that was used to enhance the ventilation of the sewer was approximately 149.978 m3/d. The concentration of H2S and CH4 in the sewers were zero, indicating that the inhaled air in the vertical stack of the building could effectively and persistently enhance the ventilation of sewers.

show abstract

Use of Air Circulation Pipes in Deep Dropshafts for Reducing Air Induction into Sanitary Sewers

Cited by 27 publications

References 14 publications

Integrating the Design of Tall Building, Wastewater Drainage Systems into the Public Sewer Network: A Review of the Current State of the Art

Integrating the Design of Tall Building, Wastewater Drainage Systems into the Public Sewer Network: A Review of the Current State of the Art

Investigation on water and air characteristics in Helicoidal Ramp Dropshafts

Enhancing the ventilation of sewers by using inhaled air in the vertical stack of a building

Contact Info

Product

Resources

About