OBJECTIVETo investigate the reduction of chlorination by-products (CBPs) precursors using the fluidized-bed biofilm reactor (FBBR).

METHODSReduction of total organic carbon (TOC), ultraviolet absorbance (UV254), trihalomethane (THM) formation potential (THMFP), haloacetic acid (HAA) formation potential (HAAFP), and ammonia in FBBR were evaluated in detail. Results The reduction of TOC or UV254 was low, on average 12.6% and 4.7%, respectively, while the reduction of THMFP and HAAFP was significant. The reduction of ammonia was 30%-40% even below 3 degrees C, however, it could quickly rise to over 50% above 3degrees C. Conclusions The FBBR effectively reduces CBPs and ammonia in drinking water even at low temperature and seems to be a very promising and competitive drinking water reactor for polluted surface source waters, especially in China.

Biofilms ; Chlorine ; Water Purification

No abstract available.
Carcinoma, Squamous Cell ; Chlorine ; Photochemotherapy

Chlorine ; Computer Simulation ; Computers, Analog ; Diffusion ; Software

OBJECTIVETo better understand the mechanism of chlorine resistance of mycobacteria and evaluate the efficiency of various disinfection processes.

METHODSInactivation experiments of one strain Mycobacteria mucogenicum, isolated from a drinking water distribution system in South China were conducted with various chlorine disinfectants. Inactivation efficiency and disinfectant residual, as well as the formation of organic chloramines, were measured during the experiments.

RESULTSThis strain of M. mucogenicum showed high resistance to chlorine. The CT values of 99.9% inactivation by free chlorine, monochloramine and chlorine dioxide were detected as 29.6 +/- 1.46, 170 +/- 6.16, and 10.9 +/-1.55 min. (mg/L) respectively, indicating that chlorine dioxide exhibited significantly higher efficiency than free chlorine and monochloramine. It was also found that M. mucogenicum reacted with chlorine disinfectants more slowly than 5. aureus, but consumed more chlorine disinfectants during longer time of contact. Lipid analysis of the cell construction revealed that 95.7% of cell membrane lipid of M. mucogenicum was composed of saturated long chain fatty acids. Saturated fatty acids were regarded as more stable and more hydrophilic which enabled the cell membrane to prevent the diffusion of chlorine.

CONCLUSIONIt was concluded that different compositions of cell membrane might endow M. mucogenicum with a higher chlorine resistance.

Chlorine ; pharmacology ; Mycobacterium ; drug effects ; Water Microbiology

The purpose of this study was to investigate effectiveness of sanitization on raw vegetables not heated in foodservice operations. Microbiological examinations of food materials and cooked food with leek Gukgalli were performed in 2 HACCP-implemented foodservices (A and B) appointed by Food and Drug Administrations, and in 2 other foodservices (C and D) not implemented HACCP. 'Washing and sanitizing raw vegetables' were monitored as CCP at A and B foodservices but only washing has been done in pre-preparation at C and D foodservices. Aerobic plate counts of received leek in A and B foodservices were above 10(7) CFU/g indicating very poor microbiological quality. After sanitization treatment (soaking for 5 minutes in chlorine water: chlorine density 50~100 ppm), its aerobic plate counts decreased to 7.06x10(5) CFU/g (A foodservice) and 4.31x10(5) CFU/g (B foodservice), coliform and faecal coliform were not detected. With this result, the effect of microbial reduction by sanitizer was conformed. But, the conditions of leek were still not acceptable by microbiological standards for ready-to-eat foods. After three more times of rinse has been done, the microbial conditions of leek became acceptable. In C and D foodservices, aerobic plate counts of leek showed decreasing trends by 2x4 times of washings but microbiological quality of leek after pre-preparation were unacceptable by microbiological standards for ready-to-eat foods (C foodservice: 3.58x10(5) CFU/g, D foodservice: 1.29x10(9) CFU/g). For the prevention of foodborne illness, sanitizing raw vegetables should be performed during pre-preparation of non-heated foods.
Chlorine ; Hazard Analysis and Critical Control Points ; Hot Temperature* ; Vegetables* ; Water

OBJECTIVETo prepare and evaluate novel chlorine dioxide-based disinfectant powder in single-pack that is more convenient for use and transportation.

METHODSOrthogonal experiment was performed to determine the recipe of the disinfectant powder. Stability test, suspension quantitative bactericidal test, simulation field trial, and animal toxicity test were carried out to observe its bactericidal and toxicological effects.

RESULTSThe orthogonal experiment showed that the type of water solution had no effect on the disinfectant powder and the best ratio of sodium chlorite to solid acid was 1:3. Ten grams of the disinfectant powder was fully dissolved in 20 mL water for 2 min, and diluted to 500 mL in water. After 5-10 min, the concentration of chlorine dioxide (ClO2) solution was 266 mg/L to 276 mg/L. After stored at 54 degrees C for 14 d, the average concentration of ClO2 was decreased by 5.03%. Suspension quantitative bactericidal test showed that the average killing logarithm (KL) value for both Staphylococcus aureus and Escherichia coli in 100 mg/L ClO2 solution for 2 min was over 5.00. in simulation field trial, the average descending KL value for Escherichia coli in the solution containing 100 mg/L ClO2 for 5 min was over 3.00. The mouse acute LD50 in the solution 5 times exceeded 5000 mg/kg. The disinfectant powder was not toxic and irritative to rabbit skin and had no mutagenic effect on mouse marrow polychromatic erythrocytes (PCE).

CONCLUSIONThe stability and bactericidal efficacy of solid chlorine dioxide-based disinfectant powder in single-pack are good. The solution containing 100 mg/L ClO2 can kill vegetative forms of bacteria. The concentration of ClO2 on the disinfecting surface of objects is 100 mg/L. The disinfectant powder is not toxic and irritative.

Chlorine Compounds ; pharmacology ; Disinfectants ; pharmacology ; Escherichia coli ; drug effects ; Oxides ; pharmacology ; Staphylococcus aureus ; drug effects

Acute Disease ; Adult ; Aged ; Asthma ; chemically induced ; Chlorine ; poisoning ; Humans ; Male

Accidents, Occupational ; Chlorine Compounds ; poisoning ; Humans ; Occupational Diseases ; chemically induced ; Oxides ; poisoning

Cardiomyopathies ; chemically induced ; Chlorine Compounds ; poisoning ; Female ; Humans ; Middle Aged ; Oxides ; poisoning

Adult ; Aged ; Chlorine ; poisoning ; Female ; Follow-Up Studies ; Humans ; Lung ; physiopathology ; Male ; Middle Aged ; Young Adult