[Microbial Properties of Different Size Aerosols at Human Average Respiratory Height During Fog-haze Days].

Size distribution and microbial population structure are typical characteristics of bioaerosols that are relevant to human health. The concentrations and population structure of bioaerosols associated with size-segregated airborne particulate matter at human average respiratory height were studied using a 6-stage Andersen impactor during and after fog-haze days in the area of Beijing. The results showed that the size distribution of the cultured microbial populations was uneven during fog-haze days, and that the microbial concentration and the difference in the population structure of the size-segregated airborne particulate matter were higher during than after the fog-haze days. During the fog-haze days, Bacillus sp. was the dominant bacteria present in bioaerosols of >3.3 µm, whereas Bacillus sp. and Bacillus amyloliquefaciens were the dominant bacteria in bioaerosols of <3.3 µm. In contrast, after the fog-haze days, Bacillus amyloliquefaciens was dominant in all the bioaerosol sizes. Five species (Alternaria sp., Penicillium italicum, Talaromyces stollii, Cladosporium sp., and Davidiella sp.) were detected as the dominant fungi in the bioaerosols >3.3 µm during the fog-haze days, and only Alternaria sp. was detected in the bioaerosols >3.3 µm after fog-haze. Penicillium italicum and Talaromyces stollii were also detected in the bioaerosols of <3.3 µm during and after the fog-haze. There were significant differences in the concentration and population structure of the size-segregated airborne particulate matter at human average respiratory height collected during and after the fog-haze days. The high concentration of microorganisms and the relatively complex population at human average respiratory height on haze days indicate that the potential risks of the microbiological characteristics of the bioaerosols to human health cannot be ignored.

[Acclimatization and Community Structure Analysis of the Microbial Consortium in Nitrate-Dependent Anaerobic Methane Oxidation].

Methane oxidation coupled with denitrification is an effective way to reduce the discharge of nitrate and methane. The anaerobic sludge from a laboratory wastewater treatment facility, anaerobic sludge from a wastewater treatment plant, and soil from a landfill were selected as inoculum to enrich the consortium for anaerobic methane oxidation in cooperation with nitrate reduction. The investigation of methane oxidation was carried out in these systems. The results showed that the maximum methane consumption rate of 0.05 mg·d-1 was obtained when the anaerobic sludge from a wastewater treatment plant served as inoculum. The population of bacteria and archaea were assayed by the clone library method. The Methanosarcinales and Methanomicrobiales were present in methane oxidation as methane oxidizing archea. The Pseudomonas, Clostridia, and Thermomonas were identified as nitrate reducing bacteria in the process of nitrate reduction. Both the methane conversion rate and microbial population varied with the amount of nitrate. The nitrate reduction bacteria were Pseudomonas and Clostridia when the nitrate concentration was 200 mg·L-1. The Pseudomonas and Thermomonas emerged when the nitrate concentration increased to 500 mg·L-1, and the rate of methane conversion was increased by 34.7%. The results provided science evidence for the co-treatment of methane and nitrate.

[Effects of Heat and Heat-alkaline Treatments on Disintegration and Dissolved Organic Matter in Sludge].

The hydrolysis of sludge organic matter is the rate-limiting step of anaerobic sludge digestion. Because pretreatments can effectively convert the solid organic matter into dissolved organic matter, it can improve the degradation rate and methane conversion rate of organic matter. In this study, the effects of heat and heat-alkaline treatments (two common pretreatments) on the composition, relative molecular weight distribution, and structure of dissolved organic matter in sludge were studied. The results showed that the heat and heat-alkaline treatments released a large amount of organic matter, which resulted in the SCOD increasing 21.9 times (heat treatment) and 47.8 times (heat-alkaline treatment). These pretreatments changed the molecular weight distribution of dissolved organic matter and decreased the molecular weight of the organic matter to the greatest degree. The results of three-dimensional fluorescence spectroscopy showed that both of the pretreatments can hydrolyze protein, the main component of sludge soluble organic matter, with the heat-alkaline treatment being more significant. In dissolved organic matter, the byproducts of the microorganisms and humic acids are not easily hydrolyzed further by the two pretreatments. In addition, the two pretreatments led to the appearance of new organic structures and the change and even disappearance of the original organic matter.

[Characteristics of Bioaerosols Emitted from WWTP with SBR Treatment Process].

Sampling sites were located in a wastewater treatment plant (WWTP) with a sequencing batch reactor activated sludge process to investigate the characteristics of bioaerosol emissions. The results indicated that bioaerosols were detected from each treatment section of the WWTP, and concentrations of bioaerosols were in the range of 82-1525 CFU·m-3. The coarse screen, aeration tank, and sludge dewatering house were the main sources of bioaerosols. The dominant species in each treatment section was Cyanobacteria, and the other main bacterial taxa were Aeromonas, Peptostreptococcaceae, Moraxellaceae, Chroococcidiopsis, Sphingomonas, Arcobacter, and Acinetobacter. Among the identified bacterial genera, Aeromonas, Arcobacter, Acinetobacter, and Sphingomonas were potential pathogens. Bioaerosol concentration and abundance decreased along the vertical and horizontal directions. Appropriate temperature and relative humidity benefited the survival of bioaerosols in the air (P<0.01), whereas a negative relationship between bioaerosol concentration and wind speed was observed (P<0.05). Although exposure risks caused by bioaerosols were negligible in this study, the accumulation of bioaerosols would increase potential health risks. The bioreactor for odor treatment could effectively reduce bioaerosol emissions.

[Evaluating the Significance of Odor Gas Released During the Directly Drying Process of Sludge: Based on the Multi-index Integrated Assessment Method].

Co-processing of sewage sludge using the cement kiln can realize sludge harmless treatment, quantity reduction, stabilization and reutilization. The moisture content should be reduced to below 30% to meet the requirement of combustion. Thermal drying is an effective way for sludge desiccation. Odors and volatile organic compounds are generated and released during the sludge drying process, which could lead to odor pollution. The main odor pollutants were selected by the multi-index integrated assessment method. The concentration, olfactory threshold, threshold limit value, smell security level and saturated vapor pressure were considered as indexes based on the related regulations in China and foreign countries. Taking the pollution potential as the evaluation target, and the risk index and odor emission intensity as evaluation indexes, the odor pollution potential rated evaluation model of the pollutants was built according to the Weber-Fechner law. The aim of the present study is to form the rating evaluation method of odor potential pollution capacity suitable for the directly drying process of sludge.

[Treatment of Flue Gas from Sludge Drying Process by A Thermophilic Biofilter].

A thermophilic biofilter was employed to treat the flue gas generated from sludge drying process, and the performance in both the start period and the stationary phase was studied under the gas flow rate of 2 700-3 100 m3 x h(-1) and retention time of 21.88-25.10 s. The results showed that the thermophilic biofilter could effectively treat gases containing sulfur dioxide, ammonia and volatile organic compounds (VOC). The removal efficiencies could reach 100%, 93.61% and 87.01%, respectively. Microbial analysis indicated that most of the population belonged to thermophilic bacteria. Paenibacillus sp., Chelatococcus sp., Bacillus sp., Clostridium thermosuccinogenes, Pseudoxanthomonas sp. and Geobacillus debilis which were abundant in the thermophilic biofilter, had the abilities of denitrification, desulfurization and degradation of volatile organic compounds.

[Performance and Mechanism of Ferric Tannate in the Removal of Inorganic Nitrogen from Wastewater].

A novel adsorbent material-ferric tannate was synthesized, and performances and mechanisms of NH4(+) -N, NO2(-) -N and NO3(-) -N were investigated via batch adsorption experiments. The results indicated that ferric tannate exhibited preferential adsorption for NH4(+) -N and NO2(-) -N. When the mass ratios of ferric tannate to NH4(+) -N and ferric tannate to NO2(-) -N were both 200, the removal efficiencies were both higher than 95%. The adsorption behaviors were analyzed with adsorption kinetic models, Langmuir and Freundlich isotherm adsorption models, and Weber-Morris equation. The results implied that NH4(+) -N and NO2(-) -N were adsorbed on the surface of ferric tannate in the forms of monolayer and multilayer, respectively. The pseudo-second order kinetic model was more suitable to describe the adsorption processes, and the external particle diffusion and surface adsorption played the key roles in the adsorption process. NH: -N could be combined with negative oxygen ions which distributed on the external surface of ferric tannate by the electrostatic interaction, whereas NO2(-) -N could be combined with ferric ions in ferric tannate by the electrostatic interaction and coordination. The present study provided scientific evidence for the application of ferric tannate as a potential adsorbent in the future.

[Characteristics of odors and VOCs from sludge direct drying process].

Co-processing sewage sludge by using the high-temperature feature of cement kiln can realize harmless disposal and energy recycling. In this paper, investigation on characteristics of the flue gas from sludge drying process was carried out in Guangzhou Heidelberg Yuexiu Cement Co., LTD. The composition and the main source of odors and volatile organic compounds (VOCs) emitted during the drying process were analyzed, aimed to provide scientific basis for the treatment of sewage sludge. Results showed that there were a large number of malodorous substances and VOCs in the flue gas. Sulfur dioxide and other sulfur-containing compounds were the main components in the malodorous substances, while benzene derivatives were predominant in VOCs. The compositions of odors and VOCs were influenced by the characteristics of the sludge and the heat medium (kiln tail gas). Total organic compounds in the sludge were significantly decreased after drying. Other organic substances such as volatile fatty acid, protein, and polysaccharide were also obviously reduced. The organic matter in sludge was the main source of VOCs in the flue gas. Part of sulfurous substances, such as sulfur dioxide, carbon disulfide, were from sulfur-containing substances in the sludge, and the rest were from the kiln tail gas itself.

[Acclimatization and characteristics of microbial community in sulphate-dependent anaerobic methane oxidation].

The greenhouse effect of methane is 26 times worse than that of carbon dioxide, and wastewater containing high concentrations of sulfate is harmful to water, soil and plants. Therefore, anaerobic oxidation of methane driven by sulfate is one of the effective ways for methane reduction. In this paper, with sulfate as the electron accepter, a microbial consortium capable of oxidating methane under anaerobic condition was cultured. The diversity and characteristics of bacterial and archaeal community were investigated by PCR-DGGE, and phylogenetic analysis of the dominant microorganisms was also carried out. The DGGE fingerprints showed that microbial community structure changed distinctly, and the abundance of methane-oxidizing archea and sulfate-reducing bacteria increased in the acclimatization system added sulfate. After acclimatization, the bacterial diversity increased, while archaea diversity decreased slightly. The representative bands in the DGGE profiles were excised and sequenced. Results indicated that the dominant species in the acclimatization system were Spirochaetes, Desulfuromonadales, Methanosarcinales, Methanosaeta. Methane converted into carbon dioxide while sulfate transformed into hydrogen sulfide and sulfur in the process of anaerobic methane oxidation accompanied by sulphate reduction.

[Analysis of the fractal structure of activated sludge flocs].

The small-angle light scattering (SALS) experiment was executed to calculate the fractal region, and the data of particle size distribution was fitted by Gamma equation. Besides, the atomic force microscope (AFM) and confocal laser scanning microscopy (CLSM) were used to observe the morphology of the microstructure of the sludge flocs under different scales. The results showed that the sluge floc was constituted by a series of clusters with different sizes. The surface of the floc was unsmooth with various "holes" and "gaps" and there were a range of pore structures within the sludge floc. For sludge flocs at large scales, a variety of pore texture coexisted, forming a transport channel for the nutrients and water in the sludge. The results also showed that the fractal structure was present in sludge flocs in the size range of 0.5-50 microm and the particle size distribution was fitted to the Gamma equation distribution model, indicating that the sludge floc formation process is a process dominated by Cluster-Cluster flocculation.

[Surface characteristics of alkali modified activated carbon and the adsorption capacity of methane].

Coconut shell based activated carbon was modified by alkali with different concentrations. The surface structures of tested carbons were observed and analyzed by SEM and BET methods. Boehm's titration and SEM/EDS methods were applied to assay the functional groups and elements on the carbon surface. The adsorption of methane on tested carbons was investigated and adsorption behavior was described by the adsorption isotherms. Results showed that surface area and pore volume of modified carbon increased and surface oxygen groups decreased as the concentration of the alkali used increased, with no obvious change in pore size. When concentration of alkali was higher than 3.3 mol x L(-1), the specific surface area and pore volume of modified carbon was larger than that of original carbon. Methane adsorption capacity of alkali modified carbon increased 24%. Enlargement of surface area and pore volume, reduction of surface oxygen groups will benefit to enhance the methane adsorption ability on activated carbon. Adsorption behavior of methane followed the Langmuir isotherm and the adsorption coefficient was 163.7 m3 x mg(-1).

[Fate analysis of NPEOs and their metabolites in municipal wastewater plants].

Nonylphenol ethoxylates (NPEOs), as an important group of non-ionic surfactants, have raised the society's serious concern because they can be transformed into their metabolites such as nonylphenol (NP) after biodegradation, which could cause potential disrupting effects on the endocrine system of wild animals. In this paper, NPEOs and their metabolites were taken as the research objects, and the occurrence and output pathways of NPEOs and their metabolites during the municipal wastewater treatment process were investigated, as well as the affecting factors of their removal efficiency. The results showed that NPEOs and their metabolites were ubiquitous in the influents of municipal wastewater plants, and the concentrations were related to seasons, geographic locations, living habits and so on. NPEOs and their metabolites entering WWTPs were output mainly through three pathways: biodegradation, adsorption onto sludge and release via effluents. Endocrine disrupting chemicals such as NP and NPECs were produced during the wastewater treatment process and entered the environment via effluents and sludge. The results of this paper could provide a scientific basis for the construction of safety control techniques in the municipal wastewater treatment plant.

Characterization of multiporous structure and oxygen transfer inside aerobic granules with the percolation model.

The characteristics of aerobic granules for wastewater treatment are greatly related to their complex internal structure. However, due to the limitation of characterizing methods, information about the granule internal morphology and structure is very sparse, and mechanism of mass transfer process is yet unclear. In this work, the internal structure of aerobic granules was explored using nitrogen adsorption method and confocal laser scanning microscopy technique. It was found that aerobic granules had multiporous structure with cross-linked gel matrix structure. With a consideration of the hydrodynamic regime and the porous structure of granules, a two-dimensional percolation model was established to describe the mass transfer in granules. With the approaches, interesting and useful results regarding the pore distribution and mass transfer in aerobic granules have been obtained. The results demonstrate that the intragranule convection could enhance mass transfer, hence ensure an efficient and stable operation of aerobic-granule-based reactors. Such approaches might also be applicable to characterizing the multiporous structure and mass transfer of other microbial aggregates for wastewater treatment.

Microscale hydrodynamic analysis of aerobic granules in the mass transfer process.

The internal structure of aerobic granules has a significant impact on the hydrodynamic performance and mass transfer process, and severely affects the efficiency and stability of granules-based reactors for wastewater treatment. In this study, for the first time the granule complex structure was correlated with the hydrodynamic performance and substrates reactions process. First, a series of multiple fluorescence stained confocal laser scanning microscopy images of aerobic granules were obtained. Then, the form and structure of the entire granule was reconstructed. A three-dimensional computational fluid dynamics study was carried out for the hydrodynamic analysis. Two different models were developed on the basis of different fluorescence stained confocal laser scanning microscopy images to elucidate the roles of the granule structure in the hydrodynamic and mass transfer processes of aerobic granules. The fluid flow behavior, such as the velocity profiles, the pathlines and hence the hydrodynamic drag force, exerted on the granule in a Newtonian fluid, was studied by varying the Reynolds number. Furthermore, the spatial distribution of dissolved nutrients (e.g., oxygen) was acquired by solving the convection-diffusion equations on the basis of the reconstructed granule structure. This study demonstrates that the reconstructed granule model could offer a better understanding to the mass transfer process of aerobic granules than simply considering the granule structure to be homogeneous.

[Characteristics of microbial community in biohydrogen production from alkali pretreated sludge].

In order to reveal the characteristics of microbial community in biohydrogen production from alkali pretreated sludge, the biohydrogen fermentation was conducted under acidic condition (pH 5) and alkali condition (pH 11) using alkali pretreated sludge from three wastewater treatment plants with different process, respectively. The results indicate that, although the sludge from different sources, protein is main component in the soluble organic matter released from the three sludge samples by the alkali pretreatment and carbohydrate is only 15% -16% of protein. A high hydrogen yield occurs at the condition of initial pH 11, a maximal hydrogen yield of up to 31.9 mL/g, while the hydrogen yield decreases and hydrogen consumption occurs at the condition of initial pH 5. The analysis using PCR-DGGE technique based on 16S rDNA sequences with the universal primers (F338GC and R534) show that the microbial community in the biohydrogen production process from various sludge structure is significant different, and the microbial population appear a phenomenon of turnover growth and decline and the amount of dominant microbial community present a increasing trend.

[Protozoan community diversity in membrane bioreactor].

Continuous monitoring on the microbial character was performed in the sludge in MBR compared with traditional active sludge process. It was found that the sludge retention time (SRT) and temperature were the dominant factors that control protozoan diversity. The extra-long SRT exhibited a negative effect on the activity of protozoa. When SRT decreased from 350 d to 30 d, protozoan diversity increased significantly. Subsequently, the structure of protozoa community in the MBR was found to be quite sensitive to environment temperature, and protozoan diversity continuously increased with the increasing temperature from 11 to 25 degrees C. The dominant population was alternate and in some order: running Ciliata, Epistylis and Opercularia, Rotifers, then Aeolosomatidae. Further analysis showed that MBR reactor harbored a lower detectable microbial diversity compared with the TOD reactor at the same temperature and SRT.

[Effect of acid and alkali on phosphorus release from sewage sludge in the microwave treatment process].

Impacts of acid and alkali addition on phosphorus release from sewage sludge were investigated in a microwave reactor at atmospheric pressure. Results showed that in the microwave irradiation process, though NaOH pretreatment increased the release efficiency of phosphorus from 28.8% to 59.1%, large amounts of carbon and nitrogen were correspondingly released into the supernatant. Compared to the alkali pretreatment, pretreatment of H2SO4 not only resulted in the higher release efficiency of phosphorus by 3 times (up to 84.5%), but also sharply reduced the amount of carbon and nitrogen released into the supernatant. These results suggest that H2SO4 pretreatment of sewage sludge can selectively release carbon, nitrogen and phosphorus, which is more suitable for phosphorus recovery from sewage sludge. Meanwhile, the pH range of 2.1-2.2 was optimal for phosphorus release from sewage sludge in the microwave treatment process.

[Impacts of different aeration modes on nutrients conservation during swine manure composting with magnesium salt addition].

Experiments were carried out to investigate the effect of two aeration modes on nutrients conservation in the thermophilic stage of swine manure composting with adding magnesium chloride. These results indicated that in the end of thermophilic stage of composting, the ammonia nitrogen losses of the piles with the intermittent aeration and with continuous aeration, were 23.56 g and 56.98 g, respectively, which means the loss of ammonia nitrogen of swine composting by the intermittent aeration was just 41.35% of that by the continuous aeration. Such loss of ammonia nitrogen resulted in 9.8% higher of the total kjeldahl nitrogen (TKN) concentration in the pile with the intermittent aeration than that with the continuous aeration. No significant difference occurred between two piles in orthophosphate, sequential extraction phosphorus and the total phosphorus (TP). However, in the pile with intermittent aeration, the percentage of the easily dissolved phosphorous forms such as H2O-P and NaHCO3-P was increased from 27.6% of TP to 66.5%, and the other pile from 27.6% to 64.9%. The TP concentrations in both piles were 17.2 g/kg in the end of thermophilic composting stage. The mixed crystals containing magnesium and phosphorus were formed in both piles of swine composting.

[Analysis of characteristics of microbial communities in membrane bioreactor and conventional activated sludge process].

A submerged MBR and CAS were used for municipal wastewater treatment to investigate their performance and the microbial community. The effluent COD concentrations of MBR and CAS were 39.6 mg/L and 62.9 mg/L on average, respectively. The effluent concentrations of NH4+-N in MBR and CAS were 6.8 mg/L and 14.5 mg/L on average, respectively. MBR demonstrated a more stable and excellent effluent quality than CAS. The microbial community in the MBR and CAS indicate a clear difference in despite of same inoculation due to operation conditions of the MBR with the lower F/M ratio, accumulation of inert substance and strong shear force in aeration. The results of DGGE indicate that the quantity of the bacteria and the change of the similarities coefficient of the microbial community in MBR are more than those in the CAS. The result of DGGE showed that the quantity of bacteria in MBR is always larger than that in CAS, on 15, 124, 186 and 230 d, the quantity of lanes are 22, 25, 24 and 20 in MBR and 19, 14, 17 and 20 in CAS, respectively. The Dice similarity index are 54.1%, 63.7%, 63.9% and 66.8% in MBR and 71.8%, 61.4%, 9.1% and 65.9% in CAS, respectively. These phenomena show that the discharge of the excess sludge from CAS results in a loss of some no-selective bacteria, and the microbial community in the MBR has higher capability acclimatized the environment variable than that in the CAS. According to the Dice coefficient of the microbial community was higher and higher during the whole operation, it was influenced by the changes of environments, e.g. influent concentration, temperature and so on.

Decomposition and mineralization of aquatic humic substances (AHS) in treating landfill leachate using the Anammox process.

Aquatic humic substance (AHS) in landfill leachate is resistant to biodegradation, especially in anaerobic habitats. However, we reported here for the first time that AHS was completely biodegraded with the anaerobic ammonium oxidation (Anammox) process. As a result of aromatic-ring cleavage and mineralization, carboxylic and aliphatic organics were significantly produced, the contents of chromophores such as quinoid and ketone were remarkably decreased to decolorize the leachate, and produced carbon dioxide along with increasing carbonate was clearly presented. Of the degraded AHS of 137 mg L(-1), 51 mg L(-1) was owed to the oxidation with sulfate of 76 mg L(-1) as electron acceptor, and the rest to other metabolic mechanism. Isolation and identification of heterotrophic bacteria revealed a diversified consortium comprising four facultative anaerobic species, Bacillus sp., Paenibacillus sp., Bacteroides sp. and Staphylococcus sp., without sulfate-reducing bacteria detected. Their contribution to AHS biodegradation and sulfate reduction under the special conditions with high oxidization-reduction potential and insufficient electron acceptors has not been known yet. Further work is underway to investigate their properties and respective duties in the consortium.