Effects of Freeze/Thaw Process on Treatment Efficiency of Low-cost Adsorbents for Highway Stormwater Treatment

Abstract

To reduce and eliminate the contaminants from runoff because of the potential for environmental effect, all opportunities should be investigated. As a first stage, problems can be solved at its source. Identified as main source of pollution, problem with the vehicles requires a reduction in the number of vehicles and the impact of vehicles on the contaminant loading of highway runoff reduction. But transportation needs are continuously increasing and this prior of solving the problems with vehicles is critical. The batch adsorption experiments provided satisfactory results for heavy metal removal efficiency from synthetic stormwater with analyzed adsorbent materials. Synthetic stormwater for the purpose of this experiment were prepared with 2 mg/l which indicates high level of metal pollution. Other factor that effect highway runoff includes climate conditions.In this study, effect on cold climate on adsorption efficiency of low-cost adsorbents was investigated. The aim of the experiment was twofold; firstly, it was to investigated whether metals are efficiently removed with the adsorbents and secondly, to investigated the desorption process on previously adsorbed metals. Results also provided information about the stability of the adsorbents. Cold climate was simulated in laboratory with freezing and thawing process.During the experiments, pH and conductivity values were measured on each sample. Olivine and bottom ash increase the pH value on simulated stormwater from pH 7 to 12 and 10, respectively. Opposite of this, pine bark decreases the pH to 4. The reduction of heavy metals was significantly improved when adsorption process with low cost adsorbent material is used as a treatment method for highway runoff. Effects of cold climate is negligible and did not have significant influence on the adsorption efficiency, desorption process or live spin on the adsorbents. The heavy metal concentration either after adsorption or desorption process is in the range of acceptable environmental standards.