[Effect of electron acceptors on anoxic phosphorus uptake of DPB].

The test of anoxic phosphate uptake of denitrifying phosphorous removal bacteria (DPB) which was cultivated during the anaerobic/ anoxic/aerobic processes was conducted at the various situations of electron acceptors. The various concentrations of nitrate or nitrite were added during the anoxic stage respectively. The conclusions stated that the anoxic phosphate uptake of DPB was rarely influenced by the concentration of nitrate with the adequate nitrate as electron acceptors. It takes 1 mg PO4(3-) -P when the consumption of NO3(-) -N is 1 mg. The nitrite could be regarded as the electron acceptor to participate into the activities of denitrifying phosphorous removal. Compared with the nitrate, the phosphorous uptake rate of DPB with nitrite was rather higher at a low concentration (NO2(-) -N with the concentration range of 5 - 20 mg/L). Furthermore, the rate of anoxic phosphorous uptake was increased with the decreased concentration of NO2(-) -N. The restraining effects related to the anoxic phosphors uptake of DPB was increased as the increase of nitrite concentration. Hence, the anoxic phosphorous uptake of DPB was entirely inhibited when the concentration of NO2(-) -N was higher than 35 mg/L.

[The inheritance of an ultra-dwarf plant mutant from upland cotton].

The inheritance of an ultra-dwarf plant mutant from upland cotton (Gossypium hirsutum L.) was studied, which showed that the mutant was controlled by single recessive quality gene. This gene was denominated as du tentatively. No similar mutant has been found in upland cotton. The mutation could not normally flower and produce bolls under natural conditions, and its mature height was only 10.5 cm. When treated with exogenous GA3, it could normally flower and boll, and plant height could reach 57.8 cm finally.

[Nitrification and denitrification in BACF for treating high ammonia source water].

A high ammonia micropolluted source water advanced treatment for ammonia removal by biological activated carbon filter was tested. The removal rate of ammonia was high than 95% when influent concentration was under 1.0 mg/L. The removal rate decreased with the influent concentration increased when the ammonia concentration was in range of 1.5 - 4.9 mg/L and the influent DO was under 10 mg/L, and the minimum removal rate was about 30%. The key factor of restrict nitrification in BACF was the influent DO. When the influent ammonia concentration was high, the DO in water was depleted quickly by nitrify and hetetrophic bacteria in 0.4 m deep of filter and the filter layer was divided to aerobic zone and anoxic zone. The denitrification was occurred in the anoxic zone, and because of very low concentration of electron donor led to accumulation of the denitrification intermediates such as NO2-. Aerobic bacteria was existed in the anoxic zone.