Acute Toxicity and Ecological Risk Assessment of Benzophenone and N,N-Diethyl-3 Methylbenzamide in Personal Care Products.

Benzophenone (BP) and N,N-diethyl-3-methylbenzamide (DEET) are two chemicals often used in personal care products (PCPs). There is a lack of systematic ecotoxicological evaluations about the two chemicals to aquatic organisms. In the present study, the acute toxic effects on Chlorella vulgaris, Daphnia Magana, and Brachydanio rerio were tested and the ecotoxicological risks were evaluated. For BP, the 96-h half-maximal effective concentration (EC50) on C. vulgaris was 6.86 mg/L; the 24-h median lethal concentration (LC50) on D. magana was 7.63 mg/L; the 96-h LC50 on B. rerio was 14.73 mg/L. For DEET, those were 270.72 mg/L, 40.74 mg/L, and 109.67 mg/L, respectively. The mixture toxicity of BP and DEET, on C. vulgaris, D. magana, and B. rerio all showed an additive effect. The induced predicted no-effect concentrations (PNECs) for BP and DEET by assessment factor (AF) method are 0.003 mg/L and 0.407 mg/L, respectively. Both are lower than the concentrations detected from environment at present, verifying that BP and DEET are low-risk chemicals to the environment.

Rapid Classification and Identification of Microcystis aeruginosa Strains Using MALDI-TOF MS and Polygenetic Analysis.

Matrix-assisted laser desorption-ionization-time-of-flight mass spectrometry (MALDI-TOF MS) was used to establish a rapid, simple, and accurate method to differentiate among strains of Microcystis aeruginosa, one of the most prevalent types of bloom-forming cyanobacteria. M. aeruginosa NIES-843, for which a complete genome has been sequenced, was used to characterize ribosomal proteins as biomarkers and to optimize conditions for observing ribosomal proteins as major peaks in a given mass spectrum. Thirty-one of 52 ribosomal subunit proteins were detected and identified along the mass spectrum. Fifty-five strains of M. aeruginosa from different habitats were analyzed using MALDI-TOF MS; among these samples, different ribosomal protein types were observed. A polygenetic analysis was performed using an unweighted pair-group method with arithmetic means and different ribosomal protein types to classify the strains into five major clades. Two clades primarily contained toxic strains, and the other three clades contained exclusively non-toxic strains. This is the first study to differentiate cyanobacterial strains using MALDI-TOF MS.

[Characteristics of microbial community and operation efficiency in biofilter process for drinking water purification].

In order to explore characteristics of microbial community and operation efficiency in biofilter (biologically-enhanced active filter and biological activated carbon filter) process for drinking water purification, Biolog and polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) techniques were applied to analyze the metabolic function and structure of microbial community developing in biofilters. Water quality parameters, such as NH; -N, NO; -N, permanganate index, UV254 and BDOC etc, were determined in inflow and outflow of biofilters for investigation of operation efficiency of the biofilters. The results show that metabolic capacity of microbial community of the raw water is reduced after the biofilters, which reflect that metabolically active microbial communities in the raw water can be intercepted by biofilters. After 6 months operation of biofilters, the metabolic profiles of microbial communities are similar between two kinds of biologically-enhanced active filters, and utilization of carbon sources of microbial communities in the two filters are 73.4% and 75.5%, respectively. The metabolic profiles of microbial communities in two biological activated carbon filters showed significant difference. The carbon source utilization rate of microbial community in granule-activated carbon filter is 79.6%, which is obviously higher than 53.8% of the rate in the columnar activated carbon filter (p < 0.01). The analysis results of PCR-SSCP indicate that microbial communities in each biofilter are variety, but the structure of dominant microorganisms is similar among different biofilters. The results also show that the packing materials had little effect on the structure and metabolic function of microbial community in biologically-enhanced active filters, and the difference between two biofilters for the water purification efficiency was not significant (p > 0.05). However, in biological activated carbon filters, granule-activated carbon is conducive to microbial growth and reproduction, and the microbial communities in the biofilter present high metabolic activities, and the removal efficiency for NH4(+)-N, permanganate index and BDOC is better than the columnar activated carbon filter(p < 0.05). The results also suggest that operation efficiency of biofilter is related to the metabolic capacity of microbial community in biofilter.

[Experimental study on removal of micro-organic pollutants for special ecosystem using ecological embankments].

An experimental model was made on the improvement of sources water quality in the Huangpu River through the construction of a special aquatic ecosystem using ecological embankments. A 6 d retention time (RT) gave the highest removal rate capacity and benefit of micro-organic pollutants. Under these conditions, the removal rates were 70.5% atrazine, 57.7% dimethyl phthalate, 72.4% phthalic acid bis (2-ethylhexyl) ester, 62.4% diethyl phthalate, and 45.1% dibutyl phthalate. The varieties of micro-organic pollutants reduced from 51 to 28. In contrast, in the control pool with hard embankment, the removal rates only reached 40.2% atrazine, 42.9% dimethyl phthalate, 54.8% phthalic acid bis (2-ethylhexyl) ester, 52.0% diethyl phthalate, and 16.2% dibutyl phthalate. Through coordination of all constituent elements of special aquatic ecosystem, significant amounts of micro-organic pollutants were removed.

[Removal of nitrogen in simulated rivers embanked by ecological concrete].

The removal of nitrogen was studied in four types of pilot-scale rivers. The embankment for rivers No. 1, 2 and 3 consisted of respectively spheriform ecological-concrete prefab-bricks, rectangular ecological-concrete prefab-bricks and square ecological-concrete prefab-bricks with 4 hemispheroids. The embankment for river No. 4 was made of concrete C25. The results show that the removal rates of NH4+ -N, NO2- -N, NO3- -N and TN of river 1 are 83.6%, 75.2%, 37.1% and 47.5% under hydraulic retention time of 2 days, 83.4%, 53.0%, 30.6% and 40.4% for river 2, 88.1%, 72.4%, 33.0% and 40.9% for river 3. Under the same condition, NH4+ -N, TN of river 4 decreasesby 61.1%, 9.1%, while NO2- -N, NO3- -N increase by 7.4%, 3.4% due to the transformation of NH4+ -N. It indicates that ecological embankment rivers can effectively remove nitrogen. Besides, the addition of pore rate in embankment structure and more rate of plant coverage are good for the removal of nitrogen in ecological embankment rivers.

[Variations of biological stability and disinfection byproduct in water distribution systems and their correlations].

Variations of assimilable organic carbon (AOC), trihalomethanes (THMs) and haloacetic acids (HAAs) in two different water distribution systems (DSs) were investigated in Shanghai, a eastern city of China. Correlations of drinking water biological stability and disinfection byproduct were analyzed. The results show that AOC and HAAs are varied based on chlorine residual and microbial activity. And their concentrations are increased by chlorine oxidation in the front part of pipe networks where high residual chlorine contents exist, while reduced by bacterial consuming in the end part pipe networks where low residual chlorine exists. Changes of THMs in DSs are influenced by residual chlorine merely, and contents have risen with the extension of pipe net. There are evident linear relationships between HAAs and AOC, and precursors of them are homologous. Contents of THMs are positively correlated with AOC. Therefore biological stability and disinfection byproduct, as two important factors of drinking water safety, present inherent relevances.

[Removal pathway and influence factors of hydroponic bio-filter method for nitrogen and phosphorus].

Study was made on the use of hydroponic bio-filter method (HBFM) for eutrophic surface water. Results show that HBFM can remove 16.8% of TN and 30.8% of TP at the hydraulic loading rate (HLR) of 3.0 m3/(m2 x d). The removal loading rate of TN and TP can accordingly reach 1.0 and 0.1 g/(m2 x d) respectively. The sedimentation of particulate nitrogen and particulate phosphorus plays a major role in nitrogen and phosphorus removal, and its contribution is 62.2% and 75.9% respectively. The optimal HLR of HBFM ranges from 3.0 to 4.0 m3/(m x d). The intension of secateur for Nasturtium officinale has some effect on its uptake rate, thus the length of cut when harvesting should be less than 10 cm. The harvesting frequency of once a month for Nasturtium officinale has no effect on nitrogen and phosphorus removal of HBFM.

[Characteristic of combined floating bed ecosystem for water purification under dynamic condition].

A new type of ecological floating bed was developed that combined hydrophyte, aquatic animal and biofilm. The dynamic pilot study on purification characteristic and mechanism of the floating bed for eutrophic was carried out. Result shows that the removal efficiencies of TN, TP and COD(Mn), are 53.8%, 86.0% and 35.4% respectively under the water exchange period of 7 days. Main purification role is played by artificial medium and aquatic macrophyte in pollutants removal, but the Corbicula fluminea introduced to food chain of combined floating bed enhances the purification effect through the ways as follows: improving the resolvability, ammonification and biodegradability of particulate organic matters, meliorating the substrate supply condition for absorption of plant and degradation of microorganism attached on artificial medium, hastening the growth and activity of microorganism.

[Characteristics of denitrifying phosphorus removal by sequencing batch reactor].

The characteristics of denitrifying phosphorus removal were studied in a laboratory sequencing batch reactor (SBR) at NO3(-)-N to COD ratio (NO3(-)-N/COD) of 0.04, 0.095, 0.125 and 0.27, respectively. Experiments showed that the transformations of pollutants correlated well to control parameters (i.e. pH, ORP and DO). In blending phase, the reaction of denitrifying phosphorus removal could be indicated by ORP, and in oxidation phase a valley concentration of TN called NAS point could be monitored by all the three parameters, among which pH was the most sensitive parameter. Both reactor efficiency and effluent quality would be improved when supernatant was discharged at NAS point. In denitrifying phosphorus removal process, NO3(-)-N was quickly transformed into intermediate products firstly and then gradually into N2 by denitrifying P-bacteria (DPBs). Carbon source had a significant influence on phosphorus removal capability of DPBs. When NO3(-)-N/COD ratio was higher than 0.095, phosphorus removal capability of DPBs enhanced with the increase of the ratio. Results indicated that NO3(-)-N/COD ratio should not be lower than 0.125 for a favorable denitrifying phosphorus removal effect.

[Potential of nitrification and denitrification in water purification system with hydroponic bio-filter method].

The potential of nitrification and denitrification of sediment and the density of ammonium-oxidizing bacteria and nitrite-oxidizing bacteria in sediment in water quality purifying system with hydroponic bio-filter method (HBFM) were measured. The variation of nitrification and denitrification potential of the sediment along the stream way was quantitatively studied. The results show that among the sediments from front, middle and retral part of the stream way, the sediment from middle part reached a maximum nitrification potential . nitrification potential of 4.76 x 10(-6) g/(g x h), while the sediment from front part reached a maximum denitrification potential of 8 .1 x 10(-7) g/(g x h). The distribution of nitrification potential accords with the ammonium-oxidizing bacteria density. The key for improving nitrogen removal efficiency of HBFM system consists in changing nitrification & denitrification region distributing and accordingly enhances denitrification process.