Zhuo Diao

Mechanism of Cu(II) Biosorption by Saccharomyces Cerevisiae

This paper studies how chemical modification influences the Saccharomyces cerevisiae adsorption on copper ion and the desorption of nitric acid, and carries out infrared spectrum analysis of native, adsorbing and desorbing saccharomyces cerevisiae. Results show that carboxyl and amino group in Saccharomyces cerevisiae play an important role in the process of adsorbing Cu(II). The adsorption on Cu(II) by Saccharomyces cerevisiae is mainly the process of surface adsorption. The process of biosorption on heavy metals is mainly reversible adsorption; however, there still exists irreversible adsorption. FTIR analysis further indicates that carboxyl and hydroxyl adsorption on Cu(II) is reversible adsorption, which amino group adsorption on Cu(II) is irreversible adsorption.

Research on How to Determine the Residue of Atrazine in the Soil

Studies on the residue of atrazine in the soil have recently aroused great concern. This article studies the methods of determining the residue of atrazine in the soil, and thus helps solve the problems of pesticide residue. Use methanol aqueous solutions (9:1) to extract the atrazine in the soil. Concentrate the methanol, then chloroform extracted. After concentrating to a defined volume, use GC-14C gas chromatographic and FED detector to determine the residue of atrazine in the soil. This research has found that the recovery rate of residue atrazine in the soil reaches 85%-90%, and the relative standard difference (RSD) is 2.3%-4.9%.

Cleaning Process Selection and Mechanism of Membrane Pollution in the Membrane Bioreactor

Membrane pollution and its cleaning technology in MBR water treatment process were tested. Membrane of short-term (22d) experiment and membrane of long-term (210d) experiment were cleaned separately by cold water rarr hot water rarr sodium hypochlorite rarr ethanol, membrane fluxes came back to the 94.4% and 70.3% of the new membranes, respectively. Another membrane of long-term (210d) experiment was cleaned with different process by cold water rarr hot water rarr sodium hypochlorite rarr sulfuric acid, membrane flux came back to the 61.4% of the new membrane. The cleaning test of membrane module showed: different cleaning process might bring different cleaning effect. Membrane pollution can be divided into biological pollution, organic pollution and inorganic pollution. They often occur simultaneously, and one kind of pollution can exacerbate another.

Isolation and Identification of Two Degrading Strains in Atrazine Contaminated Soil

Two strains named W7 and W16 were isolated by liquid enrichment culture from the corn field where atrazine has been chronically applied. Observed by gram stain and SEM, W7 belonged to gram-positive bacteria and the single cell was short bacilliform; W16 belonged to gram-negative bacteria and the single cell was spherical. Through physiological and identification and 16SrDNA sequence analysis, two strains were identified as Rhizobium sp. and Rhodobacter sphaeroides sp. respectively. W7 and W16 could degrade atratine effectively, and the biodegradation rate reaching up to 99 % after 72h cultivation in suitable conditions.

Immobilized Atrazine Degrading Bacteria by Different Material

The research chose the alginate sodium and PVA as the materials to immobilize the atrazine degrading bacteria. Four methods were adopted: alginate sodium adsorption method, alginate sodium embedding method, PVA boric cross linking method and PVA freezing method. The degrading effects and the characteristics of the atrazine degrading bacteria in the two materials were studied respectively. The result showed that the alginate sodium embedding method was the best, the most suitable temperature for the two strains was 30℃, and the most suitable pH value for the strains were among 4 to 7 in the condition of carbon source, and the most suitable pH value for the strains which used atrazine as the sole carbon and nitrogen source were 4-6. When the immobilized atrazine degrading bacteria J2 (cultured in the carbon source condition) and J6 (cultured in the condition which uses atrazine as the sole carbon and nitrogen sources), which immobilized by the alginate sodium embedding method were put into the soil, the degradation rate reached more than 95%.

Study on the Growth and Degradation Characteristics of Atrazine Degradation Strain J6

This paper mainly studies the growth and degradation characteristics of the Atrazine degradation strain J6 which is isolated from the soil, collected from the corn field in northern China with a long history of atrazine application. The growth and the degradation characteristics at different pHs and temperatures are also studied. Adding J6 into the medium by the ratio of 1 %(v/v), J6 is able to degrade the atrazine completely in 84h whose concentration in medium is 100mg/L. When the medium was cultured at 30℃ with a pH of 7, the growth and the degradation ability of J6 become best.

Planktonic Algae Community Distribution and Eutrophication Assessment of Xi Quanyan Reservoir

The distribution and composition of the planktonic algae community in Xi Quanyan reservoir was investigated, it showed the dominant species were diatom and chlorophyta. According to the comprehensive trophic state of the multiple monitoring results of the different sampling points in the entrance, centre and exit of the Xi Quanyan reservoir, calculate the comprehensive trophic state index to gain the average of the whole year: the entrance is 56.2077, the centre is 54.4001, and the exit is 55.1305, which means that the reservoir is in the slight condition. And to analysis of variance for the different sampling points, the F value is 3.548, less than F0.05, which means that the difference of the eutrophication level is not significant among the each sampling points. By the matched data t test, the differences of eutrophication level among the 3 water periods are very significant: wet season>common season>dry season.

Removal of Copper from Aqueous Solutions by Waste Biomass of Saccharomyces cerevisiae

Put dead immobilized saccharomyces cerevisiae biomass into column of continuous upflowing reactor. Study the influence of temperature, quantity of saccharomyces cerevisiae in column and initial Cu 2+ concentration on Cu 2+ adsorption. Determine optimal operating parameters of initial pH values, flow rates and quantities of saccharomyces cerevisiae in column through orthogonal experiment. Analyse adsorption mechanisms on Cu 2+ by saccharomyces cerevisiae powder through SEM. The results show optimal conditions are normal temperature, quantity of saccharomyces cerevisiae in column 80 g/L and initial Cu 2+ concentration 20 mg/L. The orthogonal experiment indicates that the optimal test condition was initial pH value 6, flow rate 5 mL/min, quantity of saccharomyces cerevisiae in column 80 g/L. SEM figures indicate that inorganic precipitation mechanism and redox mechanism might work in the process, and that the cell wall plays an important role in Cu 2+ adsorption.

Continuous Biosorption on Copper (II) and Industrial Wastewater Treatment by Saccharomyces Cerevisiae Biomass in Upflowing Reactor

Put dead immobilized saccharomyces cerevisiae biomass into column of continuous upflowing reactor, investigated immobilized materials on copper (Π) adsorption through batch adsorption procedures, breakthrough curves of different immobilized materials, initial pH values, flow rates and diameters of immobilized products were studied on copper (Π) adsorption, desorption tests and industrial wastewater treatment were analyzed. The results showed: saccharomyces cerevisiae was a perfect kind of adsorbent and feasible for removing on copper (Π) with low concentration in wastewater. The immobilized materials adsorbed little on copper (Π). Initial pH values, flow rates and diameters of immobilized saccharomyces cerevisiae products could affect copper (Π) adsorption to some extent. The desorption tests showed that 0.1mol•L-1 HCL was optimal. And immobilized saccharomyces cerevisiae biomass in continuous upflowing reactor were effective on industrial wastewater treatment.