Degradation of dissolved organic matter in effluent of municipal wastewater plant by a combined tidal and subsurface flow constructed wetland.

Affiliation

Lyu C(1), Liu R(1), Li X(2), Song Y(3), Gao H(4).
Author information:
(1)Basin Research Center for Water Pollution Control, Chinese Research Academy of Environmental Sciences, Beijing 100012, China; College of Water Sciences, Beijing Normal University, Beijing 100875, China.
(2)Basin Research Center for Water Pollution Control, Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
(3)Basin Research Center for Water Pollution Control, Chinese Research Academy of Environmental Sciences, Beijing 100012, China; College of Water Sciences, Beijing Normal University, Beijing 100875, China. Electronic address: [Email]
(4)Basin Research Center for Water Pollution Control, Chinese Research Academy of Environmental Sciences, Beijing 100012, China; College of Water Sciences, Beijing Normal University, Beijing 100875, China. Electronic address: [Email]

Abstract

Dissolved organic matter (DOM) is an important constituent of wastewater treatment plant (WWTP) effluent. A novel combined tidal and subsurface flow constructed wetland (TF-SSF-CW) of 90 L was constructed for a ten-month trial of advanced treatment of the WWTP effluent. Excitation emission matrix (EEM) fluorescence spectroscopy, parallel factor (PARAFAC) analysis and a two end-member mixing model were employed to characterize the composition and removal process of the effluent DOM (EfOM) from the WWTP. The results showed that the TF-SSF-CW performed an efficient EfOM removal with dissolved organic carbon (DOC) removal rate of 88% and dissolved organic nitrogen (DON) removal rate of 91%. Further analysis demonstrated that the EfOM consisted mainly of two protein moieties and two humic-like groups; protein moieties (76%) constituted the main content of EfOM in raw water and humic-like groups (57%) became the dominating contributor after treatment. The EfOM from the WWTP was mainly of aquatic bacterial origin and evolved to a higher proportion of terrigenous origin with higher humification in the TF-SSF-CW effluent. A common controlling treatment-related factor for determining the concentrations of the same kind of substances (protein groups or humic-like groups) was revealed to exist, and the ratio of removal rates between the same substances in treatment was calculated. Our study demonstrates that the TF-SSF-CW can be a novel and effective treatment method for the EfOM from WWTPs, and is helpful for understanding of the character of EfOM in wetland treatment.