The effect of the application of halotolerant microorganisms on the efficiency of a pilot-scale constructed wetland for saline wastewater treatment

In order to find the optimal design characteristics of constructed wet- lands for saline wastewater treatment, halotolerant microorganisms, isolated from the water of the Secovlje salterns, were inoculated into the media of a pilot-scale constructed wetland (CW). The purpose of this study was to exa- mine the influence of different salinities on the efficiency of halotolerant mic- roorganisms for the removal of pollutants in order to evaluate the possibility of their employment for saline wastewater treatment. The efficiency of ammo- nium removal (34.1 %) was the highest with 0 % NaCl in wastewater and slightly lower (31.8 %) when 2 g/dm 3 saccharose was added to aerated 1.5 % NaCl wastewater. The highest removal efficiency of chemical oxygen demand (COD) in the pilot-scale subsurface flow (SSF) CW was 83.6 % when saccha- rose (2 g/dm 3 ) was added to aerated 1.5 % NaCl wastewater. It was found that removal efficiency of the pilot-scale constructed wetland with inoculated halo- tolerant microorganisms showed a higher sensitivity to aeration and the pre- sence of saccharose than to variation of the salinity of the wastewater. It can be concluded that halotolerant microorganisms, isolated from the Secovlje sal- terns, are not sensitive to the changes in salinity and are, therefore, an alter- native in the treatment of saline wastewater with a constructed wetland. How- ever, with aeration their efficiency could be further improved.