Performance of novel constructed wetlands for treating solar septic tank effluent

Thammarat Koottatep; Tatchai Pussayanavin; Sopida Khamyai; Chongrak Polprasert

doi:10.1016/j.scitotenv.2020.142447

Performance of novel constructed wetlands for treating solar septic tank effluent

Sci Total Environ. 2021 Feb 1:754:142447. doi: 10.1016/j.scitotenv.2020.142447. Epub 2020 Sep 22.

Authors

Thammarat Koottatep¹, Tatchai Pussayanavin², Sopida Khamyai¹, Chongrak Polprasert³

Affiliations

¹ School of Environment, Resources and Development, Asian Institute of Technology, Thailand.
² School of Environment, Resources and Development, Asian Institute of Technology, Thailand; Faculty of Science, Ramkhamhaeng University, Thailand. Electronic address: poktatchai@gmail.com.
³ Thammasat School of Engineering, Thammasat University, Thailand.

Abstract

To improve treatment performance of the solar septic tank technology, novel constructed wetland systems have been proposed as an effective post-treatment system. This study aimed to investigate the treatment performance of the multi-soil layer based constructed wetland (MSL-CW) and comparing with the modified constructed wetland (mCW) for treating solar septic tank effluent in long-term operation. Pilot-scale MSL-CW and mCW units were operated in parallel under the same conditions during the period of 2016-2019. Removal efficiencies of TCOD, SCOD and TBOD in the MSL-CW were not significantly different (p < 0.05) from those of the mCW unit, which were 70-72%, 63-68% and 78-82%, respectively. The removal efficiencies of TSS, TKN, NH₄-N and TP were found in the same magnitude in both units. The total coliform and E.coli counts in the effluent of MSL-CW and mCW units were reduced from 10⁵ MPN/100 mL to be lower than 10³ MPN/100 mL. These long-term operational results demonstrated that the effluent from the MSL-CW and mCW units could meet the global standards of non-sewered sanitation systems and the WHO guidelines. The effects of seasonal variations and plant harvesting on the monthly treatment performance are discussed in this study.

Keywords: Long term performance; Modified constructed wetland; Multi-soil layer based system; Post-treatment; Solar septic tank effluent.