Search

The sanitation control of pathogens in the tropical effluents needs much more attention to ensure ecosystem health integrity and the safety of human health. The common use of chemicals in achieving this in wastewater treatment has remained unsustainable due to much health concern. Indeed, based on the numerous challenges associated with faecal pathogenic bacteria in wastewaters, the focus is now on achieving higher purification efficiencies in the elimination of the human pathogens from wastewater through eco-sustainable systems such as constructed wetlands (CWs). Hence, the need to explore the application of constructed wetlands in wastewater treatment under specific local environmental conditions for accurate understanding and improved treatment efficiency. This study therefore aimed at monitoring constructed wetlands faecal bacteria purification efficiency through integrated non-molecular membrane filtration technique and molecular quantitative polymerase chain reaction (MFT-qPCR) technique. The results showed some shortfall in the treatment system and also proved that integrating MFT-qPCR in faecal bacterial purification monitoring within a constructed wetland system provides a more accurate and reliable outcome. Additionally, the wetland purification efficiency was low (

Biodegradation of anion-surfactant (LAS) and non-ion surfactant (NIS) in water of Lake Dianchi under the different incubation conditions were studied by the 'river die-away' method in this paper. The results showed that LAS and NIS could be biodegradated by microorganisms in the water of Lake Dianchi. The percentages of degradation of LAS and NIS were more than 95% and 92% after 30 days respectively. The biodegradation of LAS and NIS flitted the second kinetic model and the correlation coefficient values were among 0.956 to 0.999. Incubation temperature, initial concentrations of surfactants, pH value and nutrients (glucose or Na2HPO4) could affect the biodegradation of LAS and NIS, Incubation temperature was the major factor influence on biodegradation of surfactant in water of Lake Dianchi. When the incubation temperature increased from 20 degrees C to 30 degrees C, the biodegradation rate of LAS increased from 0.73 d(-1) to 2.10 d(-1) and the degradation half-life of NIS reduced from 11.5 d to 4.4 d. Increased the initial concentrations of surfactants led to a little increase of the degradation half-life of LAS and NIS. The biodegradation of surfactants at pH 7 was slightly easier than that of at pH 10. The degradation of NIS and LAS could be inhibited by added glucose but be promoted by added Na2HPO4. Aeration could accelerate the degradation of LAS but had limited promotion on the degradation of NIS.

This paper analyzed the distribution and variation of microeystin ( M C) and physicochemical factors in Macun and Haidong bay of Dianchi Lake from April to December in 2003. The correlation of some physiochemical factors, including the concentration of total nitrogen, total phosphorous, dissolve oxygen, chlorophyll-a and Seechi depth, light intensity, pH, water temperature and dominance of Microcystis population, with microcystin was evaluated. Correlation analysis showed that the distribution of MC was significantly positive correlated with TN and N: P (P < 0. 01); and affected by Seechi depth, light intensity, dominance of Microcystis ( P < 0. 05). Multiple continuously factors analysis indicated that the distribution of MC in water of the two bays was mainly affected by total nitrogen, Seechi depth, chlorophyll-a, dissolve oxygen and total phosphorous (R-2= 0. 560, P < 0. 017).

The persistence time and risk of microcystin-RR (MC-RR) in cropland via irrigation were investigated under laboratory conditions. In order to evaluate the efficiency of the potential adsorption and biodegradation of MC-RR in cropland and the persistence time of MC-RR for crop irrigation, high performance liquid chromatography (HPLC) was used to quantify the amount of MC-RR in solutions. Our study indicated that MC-RR could be adsorbed and biodegraded in cropland soils. MC-RR at 6.5mg/L could be completely degraded within 6 days with a lag phase of 1-2 days. In the presence of humic acid, the same amount of MC-RR could be degraded within 4 days without a lag phase. Accordingly, the persistence time of MC-RR in cropland soils should be about 6 days. This result also suggested the beneficial effects of the organic fertilizer utilization for the biodegradation of MC-RR in cropland soils. Our studies also demonstrated that MC-RR at low concentration (10microg/L) could accelerate the growth of plants, while high concentration of MC-RR (100microg/L) significantly inhibited the growth of plants. High sensitivity of the sprouting stage plants to MC-RR treatments as well as the strong inhibitory effects resulting from prolonged irrigation further indicated that this MC-RR growth-inhibition may vary with the duration of irrigation and life stage of the plants.