Mass transfer approach and the designing of horizontal subsurface flow constructed wetland systems treating waste stabilisation pond effluent
Pilot-scale constructed wetlands (CWs) that allowed wastewater to flow with high interstitial velocities in a controlled environment were used to evaluate the possibility of using mass transfer approach to design horizontal subsurface flow constructed wetlands (HSSF-CWs) treating waste stabilisat...
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| Main Authors: | , , , , |
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| Format: | Article |
| Published: |
IWA Publishing
2019
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| Subjects: | |
| Online Access: | http://hdl.handle.net/20.500.12493/173 |
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| Summary: | Pilot-scale constructed wetlands (CWs) that allowed wastewater to flow with high interstitial
velocities in a controlled environment were used to evaluate the possibility of using mass transfer
approach to design horizontal subsurface flow constructed wetlands (HSSF-CWs) treating waste
stabilisation ponds (WSPs) effluent. Since CW design considers temperature which is irrelevant in
tropics, mass transfer approach could improve the design. HSSF-CWs were operated in batch recycle
mode as continuous stirred tank reactors (CSTR) at different interstitial velocities. The overall removal
rate constants of chemical oxygen demand (COD) at various interstitial velocities were evaluated in
mesocosms that received pretreated domestic wastewater. The mean overall removal rate constants
were 0.43, 0.69, 0.74 and 0.73 d 1 corresponding to interstitial velocities of 15.43, 36, 56.57 and
72 md 1, respectively. Results showed that the interstitial velocities up to 36 md 1 represented a
range where mass transfer effect was significant and, above it, insignificant to the COD removal
process. Since WSPs effluent has high flow rates and low organic load, it is possible to induce high
interstitial velocities in a HSSF-CW treating this effluent, without clogging and overflow. The
performance of these HSSF for tertiary treatment in tropical areas could be improved by considering
flow velocity when designing. |
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