[Research on the health risk assessment of chemical pollutants in reclaimed water used for streets watering].

It is the first time for this research to utilize the method of health risk assessment. Combining with Beijing reclaimed water project, the exposure dose level and health risk to contact people are investigated and studied. The risk assessment model is built, and the exposure parameters of occupational workers and common people are provided, when reclaimed water was used for streets watering. The health risks of 19 main chemical pollutants in reclaimed water are evaluated quantificationally. The results show that the total risk caused by carcinogens is 8.47 x 10(-)6 for occupational workers and 3.78 x 10(-6) for common people.

[Exposure assessment of various reclaimed water uses].

The exposure assessment method and model of various reclaimed water uses are built combining with Beijing reclaimed water project. Firstly the daily ingesting dose and lifetime average daily dose (LADD) of exposure people are provided via field work and monitoring analysis, which could be used in health risk assessment as quantitative reference. Take park irrigation as a example, for occupational workers, the total daily ingesting dose is 0.07 L/d, LADD of disinfection by-products(DBPs) via the respiratory route is 2.8 x 10(-7) - 1.2 x 10(-5) mg x (kg x d)(-1), LADD of DBPs via the dermal route is 5.8 x 10(-8) - 2.4 x 10(-6) mg x (kg x d)(-1). For common people, the total daily ingesting dose is 0.04-0.05 L/d, LADD of DBPs via the respiratory route is 1.1 x 10(-7) - 6.8 x 10(-6) mg x (kg x d)(-1).

[Concentration limitations of pathogenic microorganisms in reclaimed water].

Using the technique of microbial risk assessment, concentration limitations of pathogenic microorganisms for various reclaimed water uses are studied. The concentration limitations are: Escherichia coli 70 MPN/L, Salmonella 0.5 CFU/L, Shigella 0.1 CFU/100L, Hepatitis A virus 0.001 PFU/100L, Rotavirus 1.2 x 10(-3) PFU/100L, Poliovirus 0.07 PFU/100L, Coxsackie 0.04 PFU/100L, Echovirus 0.05 PFU/100L, Cryptosporidium 0.1 oocysts/100 L, Giardia lamblia 0.03 cysts/100 L.

[Study on the guideline for groundwater recharge with reclaimed water].

Groundwater recharge with reclaimed water is the most beneficial way to extend reuse applications, and has the vast development foreground. In this paper, the domestic and international applications and guidelines for groundwater recharge with reclaimed water were summarized. Based on the quality of reclaimed water and the conditions of hydrological geology, the reclaimed water quality criteria for groundwater recharge was suggested including 22 basic controlling items and 52 selective controlling items, and the control technology was presented.

[Study on bio-contact oxidation A/O process of Guanting Reservior water under low temperature].

The results of the experiments showed that biological contact A/O process could run steadily under low temperature and had better removal effect for ammonia nitrogen and had some removal effect for COD and TN from water of Guanting Reservoir. When the temperature dropped greatly, removal ratio of ammonia nitrogen dropped evidently, but gradually rose and remained at high removal level at last. Under the conditions of the experiment that the temperature was 0-5 degrees C and influent ammonia nitrogen was about 10 mg/L, ammonia nitrogen removal rate remained more than 95% at last. The change of temperature had no evident influence on removal effect of COD. And the conclusion could be got by microscope that under the temperature at 0-5 degrees C the microorganism in the biofilm still had a good activity.