Restaurant emissions removal by a biofilter with immobilized bacteria

Pseudomonas sp. ZD8 isolated from contaminated soil was immobilized with platane wood chips to produce packing materials for a novel biofilter system utilized to control restaurant emissions. The effects of operational parameters including retention time, temperature, and inlet gas concentration on the removal efficiency and elimination capacity were evaluated. Cri- teria necessary for a scale-up design of the biofilter was established. High and satisfactory level of rapeseed oil smoke removal efficiency was maintained during operation and the optimal retention time was found to be 18 s corresponding to smoke removal efficiency greater than 97%. The optimal inlet rapeseed oil smoke loading was 120 mg/(m3?h) at the upper end of the linear cor- relation between inlet loading and elimination capacity.

Systematic degradation mechanism and pathways analysis of the immobilized bacteria:Permeability and biodegradation,kinetic and molecular simulation

In order to effectively improve the degradation rate of diesel,a systematic analysis of the degradation mechanism used by immobilized bacteria is necessary.In the present study,diesel degradation mechanisms were assessed by analyzing permeability,biodegradation,adsorption kinetics,and molecular simulation.We found that bacteria immobilized on cinnamon shells and peanut shells degraded relatively high amounts of diesel(69.94%and 64.41%,respectively).The primary degradation pathways used by immobilized bacteria included surface adsorption,internal uptake,and biodegradation.Surface adsorption was dominant in the early stage of degradation,whereas biodegradation was dominant in later stages.The diesel adsorption rate of the immobilized bacteria was in agreement with the pseudo second-order kinetic model.The immobilized bacteria and diesel interacted through hydrogen bonds.

Sustained and efficient remediation of biochar immobilized with Sphingobium abikonense on phenanthrene-copper co-contaminated soil and microbial preferences of the bacteria colonized in biochar

Immobilized microbial technology has been widely used in wastewater treatment,but it has been used less frequently for soil remediation,particularly in sites that are co-contaminated with organic compounds and heavy metals.In addition,there is limited knowledge on the efficiency of remediation and microbial preferences to colonize the immobilized carriers.In this study,biochar immobilized with Sphingobium abikonense was introduced to remediate soils that were co-contaminated with phenanthrene(PHE)and copper(Cu),and the mechanisms of microbial assemblage were investigated.The immobilized microbial biochar maintained a degradation rate of more than 96%in both the first(0-6 d)and second(6-12 d)contamination periods.The addition of biochar increased the proportion of Cu bound to organic matter,and Fe-Mn oxide bound Cu in the soil.In addition,both Cu and PHE could be adsorbed into biochar pellets in the presence or absence of immobilized S.abikonense.The presence of biochar significantly increased the abundance of bacteria,such as Luteibacter,Bordetella and Dyella,that could degrade organic matter and tolerate heavy metals.Notably,the biochar could specifically select host microbes from the soil for colonization,while the presence of S.abikonense affected this preference.The autonomous selection facilitates the degradation of PHE and/or the immobilization of Cu in the soil.These results provide a green approach to efficiently and sustainably remediate soil co-contaminated with PHE and Cu and highlight the importance of microbial preference colonized in immobilized carriers.

Nitrification performance of nitrifying bacteria immobilized in waterborne polyurethane at low ammonia nitrogen concentrations

Suspended and waterborne polyurethane immobilized nitrifying bacteria have been adopted for evaluating the effects of environmental changes, such as temperature, dissolved oxygen （DO） concentration and pH, on nitrification characteristics under conditions of low ammonia concentrations. The results showed that nitrification was prone to complete with increasing pH, DO and temperature. Sensitivity analysis demonstrated the effects of temperature and pH on nitrification feature of suspended bacteria were slightly greater than those of immobilized nitrifying bacteria. Immobilized cells could achieve complete nitrification at low ammonia concentrations when DO was sufficient. Continuous experiments were carried out to discuss the removal of ammonia nitrogen from synthetic micropollute source water with the ammonia concentration of about 1mg/L using immobilized nitrifying bacteria pellets in an up-flow inner circulation reactor under different hydraulic retention times （HRT）. The continuous removal rate remains above 80% even under HRT 30 min. The results verified that the waterborne polyurethane immobilized nitrifying bacteria pellets had great potential applications for micro-pollution source water treatment.

In-situ nitrogen removal from the eutrophic water by microbial-plant integrated system

Objective: This study was to assess the influence of interaction of combination of immobilized nitrogen cycling bacteria (INCB) with aquatic macrophytes on nitrogen removal from the eutrophic waterbody, and to get insight into different mechanisms involved in nitrogen removal. Methods: The aquatic macrophytes used include Eichhornia crassipes (sum-mer-autumn floating macrophyte), Elodea nuttallii (winter-growing submerged macrophyte), and nitrogen cycling bacteria in-cluding ammonifying, nitrosating, nitrifying and denitrifying bacteria isolated from Taihu Lake. The immobilization carriers materials were made from hydrophilic monomers 2-hydroxyethyl acrylate (HEA) and hydrophobic 2-hydroxyethyl methylacrylate (HEMA). Two experiments were conducted to evaluate the roles of macrophytes combined with INCB on nitrogen removal from eutrophic water during different seasons. Results: Eichhornia crassipes and Elodea nuttallii had different potentials in purification of eutrophic water. Floating macrophyte+bacteria (INCB) performed best in improving water quality (during the first experiment) and decreased total nitrogen (TN) by 70.2%, nitrite and ammonium by 92.2% and 50.9%, respectively, during the experimental period, when water transparency increased from 0.5 m to 1.8 m. When INCB was inoculated into the floating macrophyte system, the populations of nitrosating, nitrifying, and denitrifying bacteria increased by 1 to 2 orders of magnitude compared to the un-inoculated treatments, but ammonifying bacteria showed no obvious difference between different treatments. Lower values of chlorophyll a, CODMn, and pH were found in the microbial-plant integrated system, as compared to the control. Highest reduction in N was noted during the treatment with submerged macrophyte+INCB, being 26.1% for TN, 85.2% for nitrite, and 85.2% for ammonium at the end of 2nd experiment. And in the treatment, the populations of ammonifying, nitrosating, nitrifying, and de-nitrifying bacteria increased by 1 to 3 orders of magnitude, as compared to the un-inoculated treatments. Similar to the first ex-periment, higher water transparency and lower values of chlorophyll a, CODMn and pH were observed in the plant+ INCB inte-grated system, as compared to other treatments. These results indicated that plant-microbe interaction showed beneficial effects on N removal from the eutrophic waterbody.

Mercury removal and recovery by immobilized Bacillus megaterium MB1

From several mercury removing microorgan- isms, we selected Bacillus megaterium MB 1, which is non- pathogenic, broad-spectrum mercury resistant, mercuric ion reducing, heat tolerant, and spore-forming, as a useful bacterium for bioremediation of mercury pollution. In this study, mercury removal performance of the immobilized B. megaterium MB1 was investigated to develop safe, efficient and stable catalytic bio-agent for mercury bioremediation. The results showed that the alginate gel immobilized B. megaterium MB 1 cells efficiently removed 80% of mercury from the solution containing 10mg/L mercuric chloride within 24 h. These cells still had high activity of mercury removal even after mercuric ion loading was repeated for nine times. The analysis of mercury contents of the alginate beads with and without immobilized B. megaterium MB1 suggested that a large portion of reduced metallic mercury was trapped in the gel beads. It was concluded that the alginate gel immobilized B. megaterium MB 1 cells have potential to remove and recover mercury from mercury-containing water.

Immobilization of nitrite oxidizing bacteria using biopolymeric chitosan media

The effects of chitosan characteristics including the degree of deacetylation, molecular weight, particle size, pH pretreatment and immobilization time on the immobilization of nitrite-oxidizing bacteria （NOB） on biopolymeric chitosan were investigated. Nitrite removal efficiency of immobilized NOB depended on the degree of deacetylation, particle size, pH pretreatment on the surface of chitosan and immobilization time. Scanning electron microscope characterization illustrated that the number of NOB cells attached to the surface of chitosan increased with an increment of immobilization time. The optimal condition for NOB immobilization on chitosan was achieved during a 24-hr immobilization period using chitosan with the degree of deacetylation larger than 80% and various particle size ranges between 1-5 mm at pH 6.5. In general, the NOB immobilized on chitosan flakes has a high potential to remove excess nitrite from wastewater and aquaculture systems.

High-efficiency removal of NOx by a novel integrated chemical absorption and two-stage bioreduction process using magnetically stabilized fluidized bed reactors

To enhance the bioregeneration of Fe(II)EDTA and to avoid the inhibition of the components in nitrogen oxides(NOx) scrubbing solution, a novel integrated process of metal chelate absorption and two-stage bioreduction was developed. In this process, magnetically stabilized fluidized beds(MSFB) were used as the bioreactors, and the phase diagram for the MSFB operation was determined. Factors including inlet NO, O2 and SO2 concentrations, magnetic field intensity, gas flow rate and liquid circulation rate, were studied experimentally to investigate their effects on NO removal. In addition, a mathematical model for NO removal in this integrated system was developed. The results revealed that the integrated system could be steadily operated with a high NO removal efficiency and elimination capacity, even under the condition of high NO and O2 shock-loading. The established model showed that NO removal efficiency was related to the spray column property and the active Fe(II)EDTA concentration, while the latter depends on the bioregeneration of the disabled absorbent in the MSFB.