Surfactant solutions are commonly used for the remediation of petroleum-contaminated soil due to their good petroleum removal performance, time-saving capability, and cost effectiveness. However, applying surfactants in excess concentrations could make oil recovery difficult. Moreover, residual surfactants in soil are toxic to microorganisms and plants. Thus, it is crucial to identify a suitable surfactant concentration for soil washing applications. The main objective of this study was to evaluate the effect of soil minerals (quartz and kaolin) and organic matter (OM) on the critical micelle concentration (CMC) of polyethoxylated sorbitan ester surfactants (Tween 20, 40, 60, and 80) and its effect on diesel removal from dieselcontaminated soil by soil washing. The results showed that Tween surfactants with shorter carbon chain lengths required higher CMC for diesel removal from quartz, while those with longer chains needed higher CMC for kaolin cleanup. FTIR results illustrated that oxygenated functional groups of Tween surfactants played an important role in their adsorption on quartz, while alkyl chains of Tween surfactants were responsible for their adsorption on kaolin. At a certain OM concentration, quartz and OM exhibited antagonistic effects, resulting in CMC reduction. In soil washing application, maximum diesel removal could be achieved from kaolin, in the presence of which surfactants exhibited the highest CMC. Based on FTIR results, the adsorbed surfactant could reduce the hydrophobicity of the kaolin surface, thus preventing the re-deposition of detached diesel.

17α-ethinylestradiol (EE2), a synthetic estrogen which interfere the endocrine and reproductive function in living organisms, has been found extensively to be deposited into municipal wastewater treatment plants and the environment via human excretion. EE2 has long been known to be efficiently cometabolized by ammonia-oxidizing bacteria (AOB) during ammonia (NH3) oxidation. Current study aims to investigate the effect of culture history on the biotransformation of EE2 by nitrifying sludge which was enriched under different ammonia loading rates in continuous flow reactors. Result showed that past growth condition largely affected not only the metabolic rate of NH3 oxidation but also EE2 cometabolism. Sludge previously acclimated with higher NH3 loads as well as sludge dominated with AOB belong to high growth cluster (Nitrosomonas europaea-Nitrosococcus mobilis) showed higher rate of EE2 biotransformation than those one being acclimated with lower NH3 loads because of its ability to provide more reducing power from NH3 oxidation. Moreover, the correlation between the degradation rates of NH3 and EE2 was higher in sludge being acclimated with higher load of NH3 in comparison with other sludge. Implication of the findings emphasized the role of volumetric NH3 loading rate in determining EE2 removal in wastewater treatment system.

Surfactant solutions are commonly used for the remediation of petroleum-contaminated soil due to their good petroleum removal performance, time-saving capability, and cost effectiveness. However, applying surfactants in excess concentrations could make oil recovery difficult. Moreover, residual surfactants in soil are toxic to microorganisms and plants. Thus, it is crucial to identify a suitable surfactant concentration for soil washing applications. The main objective of this study was to evaluate the effect of soil composition (sand, silt, clay and organic matter), surfactant structure (Tween 20, 40, 60 and 80, and Tergitol 15-S-7, 9 and 15). Subsequently, two surfactants from each series (Tween and Tergitol) were selected for diesel removal from diesel-contaminated soil by surfactant-assisted soil washing. Then the optimizing condition was examined based on physical factors, i.e., shaking speed, Liquid: Solid (L/S) ratio and time. The results showed that Tween surfactants with shorter carbon chain lengths required higher CMC for diesel removal from sand, while those with longer carbon chains needed higher CMC for clay cleanup. Tergitol surfactants with less ethoxylate group on the hydrophilic head have higher CMC in all soil texture. At a certain OM concentration, OM exhibited antagonistic effects with sand and silt, resulting in CMC reduction. In soil washing application, the mixture design shows that maximum diesel removal could be achieved from sand. Interestingly, there are high diesel removal efficiency from soil with highly clay, which surfactants exhibited the highest CMC. Based on FTIR results, the adsorbed surfactant could reduce the hydrophobicity of the clay surface, thus preventing the re-deposition of detached diesel. The soil with highly clay content was found in most area of Thailand. Therefore, Tween 80 and Tergitol 15-S-15, which have high diesel removal efficiency in clay, were selected. In optimizing physical condition test, effect of shaking speed and L/S ratio were tested. The result showed that shaking speed was more significant and the optimal physical condition was 3:1 L/S ratio with shaking speed at 100 rpm. At these conditions, time has no significant effect.