04266nas a2200433 a 4500 20260818095940.0 080821s2008 th uu|m rtt 0| a1eng d .b1200831x AIT Diss. no.EV-08-6 Varangkana Visesmanee Engineering conditions of constructed wetlands for cadmium removal and toxicity reduction Pathum Thani, Thailand : Asian Institute of Technology, 2008 83 leaves : ill. Dissertation ; no. EV-08-6 A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Environmental Engineering and Management Inter-University Program on Environmental Toxicology, Technology and Management Thesis (Ph.D.) - Asian Institute of Technology - Chulabhorn Research Institute - Mahidol University, 2008 This study was conducted to investigate the long-term performance of subsurface-flow constructed wetland (SFCW) units treating a wastewater containing Cadmium (Cd). The hydraulic retention time (HRT) was found to have significant effects on the chemical oxygen demand (COD) and total nitrogen (TN) removal, SFCW units operating at the HRT of 8 days yielded the best treatment efficiencies with COD and TN removal of 93 and 94 %, respectively and the first order kinetic coefficient (k₂₀) of COD and TN removal were found to be 0.23 and 0.24 d⁻¹, respectively. The Cd removal efficiencies of SFCW units operating at the HRT of 1, 3, 5 and 8 days were found to be 50, 92, 98 and 99 % corresponding to the average effluent Cd concentrations of 8.3±0.6, 1.8±0.4, 0.7±0.6 and 0.2±0.1 mg/L, respectively. The Cd was removed about 70-77 % by retaining in SFCW beds due to such mechanisms as adsorption, sedimentation and filtration. Most of retained Cd in SFCW wetland media was found to be in the Fe/Mn bound and residual fractions that would remain insoluble in SFCW beds. However, plant uptake also played the role for Cd removal which was contributed about 62S %. The Cd fractions in the SFCW effluent were mostly found in the Cd ion. The Cd complex form was found to increase with increasing HRTs, Based on adsorption mechanism only, the maximum Cd adsorbed on the SFCW media was found to be 78 g, which was later used to calculate breakthrough times of Cd in the SFCW effluent. The calculated breakthrough times of the SFCW units operating at the HRT of 1, 3, 5 and 8 days were found to be 56, 166, 278 and 433 days, respectively. However, the observed Cd breakthrough times from the experiments were found to be longer than the calculated values which were probably caused by other mechanisms such as sedimentation, filtration and plant uptake. The XTT cytotoxicity test with T47D human breast cancer cells suggested the effluent from SFCW units operating at the HRTs of 5 and 8 days could reduce Cd toxicity; while Microtox technique by bioluminescent bacteria showed the toxicity reduction of the effluent for all HRTs Cadmium Physiological effects Constructed wetlands Chongrak Polprasert, Chairperson Jutamaad Satayavivad, Co-Chairperson Apinya Thiantanawat, Examination committee Gallardo, Wenresti G., Examination Committee Chulabhorn Research Institute Scholarship donor Mahidol University, Scholarship donor Asian Institute of Technology Fellowship, Scholarship donor Asian Institute of Technology. Dissertation ; no. EV-08-6 Full-Text http://203.159.5.9/ait-thesis/detail.php?q=B00544 .b1200831x mnait u 240401 0 080821 m a u 0 mnait mnarc 22 40 Barcode : 30050120725758 CREATED : 2012-08-16 RECORD # : i12686931 LPATRON : 0 LCHKIN : - # RENEWALS : 0 # OVERDUE : 0 IUSE3 : 0 TOT CHKOUT : 0 TOT RENEW : 0 Barcode : 30050160004312 CREATED : 2016-09-02 RECORD # : i12878789 LPATRON : 0 LCHKIN : - # RENEWALS : 0 # OVERDUE : 0 IUSE3 : 0 TOT CHKOUT : 0 TOT RENEW : 0 37880 37880 0 0 0 0 MAIN MAIN mnait 2026-08-18 0 AIT Diss. no.EV-08-6 30050120725758 2026-08-18 09:59:40 3 2026-08-18 22 0 0 0 0 MAIN MAIN mnarc 2026-08-18 0 AIT Diss. no.EV-08-6 30050160004312 2026-08-18 09:59:40 2026-08-18 40