Removal of Lead from Synthetic Wastewater using Aquatic Plants

AbstractAbilities of aquatic plant species, Echinodosus cordifolius (L.) Griseb., Bacopa caroliniana (Walt.) Rob., and Hydrocotyle umbellata L., for phytoremediation of lead (Pb) from synthetic wastewater were conducted in hydroponic system at 20-80 mg/L of Pb (II) and 7-28 days of exposure periods. Additional experimental set up for aquatic plant species under 60 and 80 mg/L of Pb (II) were added with 5 mM EDTA in order to enhance Pb accumulation in the plants. Results revealed that the capacity of Pb (II) accumulation at 80 mg/L of Pb (II), 28 days in roots of all aquatic plants was higher than that of shoots. E. cordifolius (L.) Griseb. had the highest capacity of Pb (II) accumulation about 12,566 (roots) and 8,686 (shoots) mg/kg dry wt, respectively giving 95% of Pb (II) removal, followed by H. umbellata L. and B. caroliniana (Walt.) Rob., respectively. Regarding EDTA addition, lead accumulation (80 mg/L of Pb (II), 7 days) was increased in the roots of H. umbellata L. about 19,883 mg/kg dry wt and it was increased in the shoots of E. cordifolius (L.) Griseb. about 14,516 mg/kg dry wt (80 mg/L of Pb (II), 21 days), respectively. The highest relative growth (13.85) and percentage of biomass productivity (98%) were in H. umbellata L. (60 mg/L of Pb (II), 7 days), whereas the highest bioconcentration factor (9,341.68) was in E. cordifolius (L.) Griseb.(80 mg/L of Pb (II), 21 days). According to the results, E. cordifolius (L.) Griseb. was recommended to remove the lead from synthetic wastewater with EDTA addition. Further studies in contaminated wastewater under various characteristics and flows should be investigated

Efficiency of Modified Grease Trap for Domestic Wastewater Treatment

AbstractThe objective of study was to investigate the efficiency of modified grease trap for domestic wastewater treatment. The study was focused on a media arrangement (5 cm diameter of Mon brick: 1 cm diameter of gravel: 3 cm diameter of Mon brick) with the different media ratios (1:1:1, 1:1:2, 2:1:1, 1:2:1, 2:2:1, 2:1:2 and 1:2:2) in a modified grease trap. Also, it was focused on the optimal factors; flow rate (2-5 L/min) and hydraulic retention time (HRT) (4-10 hrs) on treatment efficiency of grease trap. The result revealed that modified grease trap (1:1:2) for domestic wastewater treatment was generated in the highest efficiency. Suspended solid (SS), fat oil and grease (FOG) and biochemical oxygen demand (BOD) removals were up to 80%.  Moreover, it was found that the optimal flow rate and HRT for simple and modified grease (1:1:2) traps were at 2 L/min and 10 hrs. At the optimal condition; SS, BOD, and FOG removals were over 87, 70, and 87%, respectively. In a comparative study of treatment efficiency between simple and modified grease (1:1:2) traps, it showed that, under the same condition     (2 L/min, HRT varied at 4, 6, 8 and 10 hrs), a modified grease trap generated the higher efficiency of SS, FOG and BOD removal than that of a simple grease trap.

Adaptive and cross-protective responses against cadmium and zinc toxicity in cadmium-resistant bacterium isolated from a zinc mine

Cadmium (Cd) is a major environmental hazard, which usually is detected in its ionic form of Cd2+. It also causes adverse toxic effects on human health and other living organisms. Cd-resistant bacteria were isolated from Cd-contaminated soils. One isolate, TAK1, was highly resistance level to Cd toxicity. TAK1 was isolated from soil contaminated with a high Cd concentration (204.1 mg.kg-1). The result of 16S rDNA sequence analysis found that the TAK1 showed the similarity to Ralstonia sp. Physiological adaptive and cross-protective responses to Cd and Zn killing were investigated in Ralstonia sp.TAK1. Exposure to a low concentration of Cd induced adaptive resistance to higher concentrations of Cd. In addition, pretreatment of Ralstonia sp.TAK1 with an inducing concentration of Cd conferred cross-protective response against subsequent exposure to the lethal concentrations of Zn. The induced adaptive and cross-protective response Ralstonia sp.TAK1 required newly synthesized protein(s). Cd-induced adaptive and cross-protective responses against Cd and Zn toxicity are the important mechanisms used by Ralstonia sp.TAK1 to survive in the heavy metal contaminated environments. These findings might lead to the use of Ralstonia sp.TAK1 for microbial based remediation in Cd and Zn-contaminated soils