Aerobic transformation of BDE-47 by a Pseudomonas putida sp. strain TZ-1 isolated from PBDEs-contaminated sediment.

A bacterial isolate, TZ-1, was isolated from contaminated sediment near electronic waste dismantling workshops, Taizhou, China that degraded 2,2',4,4'-tetrabrominated diphenyl ether (BDE-47). The isolate was identified as Pseudomonas putida sp. with respect to its morphology, biochemical characteristics and 16SrDNA sequence analysis. TZ-1 can use BDE-47 as the sole carbon and energy source for growth in mineral salt medium. The isolate degraded BDE-47 up to 49.96 % of the initially applied concentration of 50 µg L(-1) after 7 days of incubation at 150 rpm, 30°C. Static conditions with pH 6.5 and temperature 30°C were considered to be optimum for BDE-47 biodegradation. Addition of co-substrates promoted cell growth, but decreased the degradation rate for BDE-47.

[Effects of Various Combinations of Fertilizer, Soil Moisture, and Temperature on Nitrogen Mineralization and Soluble Organic Nitrogen in Agricultural Soil].

An 84-day laboratory incubation experiment was conducted to investigate the effects of different fertilizers (urea; manure), moisture conditions (60%, 75% and 90% water holding capacity) and temperatures (15, 25 and 35℃) on nitrogen mineralization. The experiment included 3 treatments:①CK, unfertilized control; ② Ur, adding urea at N 120 mg·kg-1; 3 UM, adding urea and manure (equal to adding N 120 mg·kg-1). Total inorganic nitrogen and soluble organic nitrogen (SON) were determined at different times throughout the experiment. The results showed that soil temperature and fertilization type had significant impacts on the net mineralization rates, cumulative mineralization, and the potentially mineralizable nitrogen (N0) (P<0.01). In addition, the soil net N mineralization rates and cumulative mineralization significantly (P<0.05) increased by 1.46-8.17 and 2.00-8.15 times, respectively, when fertilizers were added into soils. The soil net N mineralization rates and cumulative mineralization increased with the increase of temperature. Compared with CK treatment, Ur and UM treatments could significantly increase the content of soil soluble organic nitrogen(SON). There was a significant negative correlation between the content of SON and cumulative mineralization. It indicated that SON was involved in soil nitrogen mineralization as a non-negligible component. Increasing the temperature could significantly increase the mineralization rate and mineralization intensity of SON in soil, but the water content had no significant influence on the SON of the soils. Moreover, the authors found that fertilization treatment worked significantly in decreasing the Q10 value for soil N mineralization compared with CK treatment. Further, the Q10 value was significantly lowest in UM treatment(Q10=1.01). The results showed that the application of organic manure significantly reduced the sensitivity of the rate of nitrogen mineralization to temperature changes, which was beneficial in slowing down the release rate of mineral nitrogen under high temperatures and improving the nitrogen utilization efficiency of crops.

Anaerobic biodegradation of benzene series compounds by mixed cultures based on optional electronic acceptors.

A series of batch experiments were performed using mixed bacterial consortia to investigate biodegradation performance of benzene, toluene, ethylbenzene and three xylene isomers (BTEX) under nitrate, sulfate and ferric iron reducing conditions. The results showed that toluene, ethylbenzene, m-xylene and o-xylene could be degraded independently by the mixed cultures coupled to nitrate, sulfate and ferric iron reduction. Under ferric iron reducing conditions the biodegradation of benzene and p-xylene could be occurred only in the presence of other alkylbenzenes. Alkylbenzenes can serve as the primary substrates to stimulate the transformation of benzene and p-xylene under anaerobic conditions. Benzene and p-xylene are more toxic than toluene and ethylbenzene, under the three terminal electron acceptors conditions, the degradation rates decreased with toluene > ethylbenzene > m-xylene > o-xylene > benzene > p-xylene. Nitrate was a more favorable electron acceptor compared to sulfate and ferric iron. The ratio between sulfate consumed and the loss of benzene, toluene, ethylbenzene, o-xylene, m-xylene, p-xylene was 4.44, 4.51, 4.42, 4.32, 4.37 and 4.23, respectively; the ratio between nitrate consumed and the loss of these substrates was 7.53, 6.24, 6.49, 7.28, 7.81, 7.61, respectively; the ratio between the consumption of ferric iron and the loss of toluene, ethylbenzene, o-xylene, m-xylene was 17.99, 18.04, 18.07, 17.97, respectively.

Influence of biosurfactant on the diesel oil remediation in soil-water system.

There were six high diesel oil degrading bacteria strains isolated from the oil contaminated soil that collected from Linzi City. The strain Y1 was able to produce biosurfactant rhamnolipid when cultivated on diesel oil as carbon source. The critical micelle concentrations (CMC) of rhamnolipid in water and in the soil were measured respectively according to the correlation between the surface tension of the medium and the added rhamnolipid concentration. The results showed that the CMC of rhamnolipid in water was 65 mg/L, and was 185 mg/L in soil. The tests on diesel oil biodegradation were conducted with the addition of different concentrations of rhamnolipid in water and in soil respectively. When 0.01% rhamnolipid was added to water, the diesel oil degradation was enhanced. On the contrary, when the same concentration of rhamnolipid was added to the soil, the degradation of diesel oil was inhibited. The results suggested that the rhamnolipid could enhance the diesel oil biodegradation, indicating that the concentration of rhamnolipid was higher than the corresponding CMC in the medium. Kinetics parameters for the diesel oil biodegradation parameters such as biodegradation constant (lambda), coefficient of correlation (r) and half life (t1/2) in both tests were numerically analyzed in this paper, indicating that the moderate concentration of rhamnolipid in the medium could not only enhance the extent of diesel oil biodegradation but also shorten the time for oil remediation.

Degradation of crude oil by indigenous microorganisms supplemented with nutrients.

Different kinds of mineral nutrients(NO3-N, NH4-N and PO4-P) were applied in the simulated oil-polluted seawater for enhancing oil biodegradation in the N/P ratio 10:1 and 20:1. Although indigenous microorganisms have the ability to degrade oil, adding nutrients accelerated biodegradation rates significantly. For the group amended with NO3-N and PO4-P in the ratio 10:1, the reaction rate coefficient was 4 times higher than the natural biodegradation. Chemical and microbiological analysis showed that the optimal N/P ratio in the system is 10:1, and microorganisms tend to utilize nitrate rather than ammonium as N source.

Volatilization behaviors of diesel oil from the soils.

The volatilization of diesel oil, Shengli crude oil and 90 # gasoline on glass surface of petri dishes were conducted at the ambient temperature of 25 degrees C. Diesel oil evaporates in a power manner, where the loss of mass is approximately power with time. 90 # gasoline evaporates in a logarithmic with time. Where as the volatilization of Shengli crude oil fit either the logarithmic or power equation after different time, and has similar R2. And the effects of soil type and diesel oil and water content on volatilization behavior in unsaturated soil were studied in this paper. Diesel oil and water content in the soils play a large role in volatilization from soils. Appropriate water helps the wicking action but too much water stops it. The wicking action behaves differently in four different types of soils in the same volatilization experiment of 18% diesel oil content and air-dry condition.

[Volatilization behavior of BTEX on different underlying materials].

Volatilization behavior of benzene, toluene, ethylb-enzene and xylene (BTEX) behaves complicatedly with different characteristics of the underlying materials. For the need to control and take precautions against volatile organic compounds (VOCs) leak and pollution, and consider the diversification of underlying materials in the area of petroleum works, the test was carried out to study the volatilization behavior of BTEX on three kinds of typical underlying materials in Zibo, Shandong, China. The studies include volatilization dynamic curves of BTEX compounds and mixture and the optimized simulation formulas for them in the base of volatilization kinetics model. The results indicated that, under the same condition, volatility speed of BTEX compounds and mixture was Benzene > Toluene > BTEX > Dimethyl-benzene > Ethylbenzene, and for the three underlying materials, the order of volatility speed was water, sand and soil in sequence. The volatility coefficient linear positive correlated with the vapor pressure, the volatility coefficient remarkably increased with the vapor pressure of BTEX compounds on all the three underlying materials. The mechanism of underlying materials acted on volatilization of BTEX were mainly shown as increasing volatility area and influence the available original (amount) of pore in the course of volatilization and spread.

[Adsorption of aqueous oil on sands and its studies of effective factors].

Representative sands were sampled on the basis of the investigation into the oil contamination of soil-water systems in the Jiaozhou-Bay. Kinetic curves and isotherms of aqueous oil adsorption on sands were measured and the influence of sand contents, sands under different size, temperature, pH and salt contents on the adsorption were studied. The research results show that dynamic curves of aqueous oil adsorption for sands are logarithmic and all the adsorption isotherms are straight, the equilibrium period of the adsorption is 6-10 hours, adsorption of aqueous oil on sands decreases with the increase of the sand contents, temperatures and pH, while increases with the increase of salinity and the more fine of the sands sizes. In addition, it was found that the sands release some oil when the aqueous oil concentrations are lower than certain values.

[Effect of nitrite on aerobic phosphate uptake by phosphate accumulating organisms].

Effect of nitrite at various concentration levels on aerobic phosphate uptake was investigated through a series of batch experiments. Furthermore, the effect of nitrite accumulated in the process of nitrification on aerobic phosphate uptake was studied in saline wastewater treatment. The results show that NO2(-) -N concentration of 4 mg/L inhibits aerobic phosphate uptake by phosphate uptake by phosphate accumulating organisms (PAO) and phosphate uptake rate decreases 8%. Exposure to higher nitrite concentration levels inhibits aerobic phosphate uptake severely. At NO2(-) -N concentration of 15 mg/L, phosphate uptake rate decreases 61%. The toxic effect of nitrite is presumed to be linked with free nitrous acid (FNA). Significant inhibition on aerobic phosphate uptake appeared at 0.000 2 mg/L of FNA concentration. The inhibiting effect of nitrite is found to occur only when nitrite is present. The ability of accumulating phosphate resumes afternitrite is no longer present. During the process of nitrification of nitrification of saline wastewater, the inhibition of nitrite on aerobic phosphate uptake is slight at the initial 1 - 2 h due to low nitrite accumulation. With the build-up of NO2(-) -N(up to about 8 to 9 mg/L), the inhibiting effect of nitrite increases gradually. It is found that higher ammonium concentration causes lower pH value and higher FNA concentration, which could decrease the amount of phosphate uptake.