脱氮硫杆菌的脱硫特性及其处理恶臭物质硫化氢的应用

污水和污泥的处理过程中会产生大量的恶臭气体硫化氢(H2S)。脱氮硫杆菌是氧化H2S和其他硫化物的重要的脱硫工程菌。本文阐述了脱氮硫杆菌的生物学特性和氧化H2S的两种途径。分析了反应体系中的硫化物负荷、硝酸盐和亚硝酸盐的浓度、氧含量以及pH值等因素对氧化效果、反应速率、氧化途径及产物形式的影响。介绍了脱氮硫杆菌在恶臭污染治理中的应用及其在同步处理含氮含硫恶臭物质方面的发展趋势。     

Spatial variation of redox and trace metal geochemistry in a minerotrophic fen

Pore water and solid phase samples were collected from the upper 50 cm of a peat profile at four sites within a 10 m² area in Kleinstuck Marsh, a minerotropic fen located in Kalamazoo, MI. Although the chosen sites are in close proximity to each other, they differ with respect to vegetation species and density. Pore water analyses for a suite of redox sensitive species (pH, alkalinity, dissolved Mn(II), Fe(II), Fe(III), sulfide, sulfate), together with Fe and Mn distributions inferred from operationally-defined sequential extractions, demonstrate that Fe(III) and Mn(IV) reduction occurs in the shallow peat at three of the four sites. At the fourth site, the only site containing the invasive purple loosestrife (Lythrum salicaria), accumulation of dissolved sulfide in the pore waters and increased levels of oxidizable phases in the shallow peat point to increased net sulfate reduction relative to the other three sites. Speciation calculations indicate that pore water concentrations of phosphate, especially below ∼10 cm depth, are largely controlled by the solubility of phases such as strengite or hydroxylapatite, and that at all but the loosestrife site, dissolved Ca and Mg are likely determined by carbonate solubility. Fe and Mn distribution among operationally defined solid phase fractions are consistent with reductive dissolution of FMO in the uppermost peat, leading to precipitation of Fe sulfides and Mn carbonates deeper in the peat profile. Zn, Co, Cr and Ni distributions are consistent with release from FMO to form sulfides or organic associations deeper in the peat. Pb and Cu may also be released by reductive dissolution of FMO, or more likely, shift from primary association with organic matter to increased association with sulfides under more sulfidic conditions. This study highlights the existence of extreme lateral variations in peat pore water and solid phase geochemical profiles, even over quite small areas.     

Analysis of copper corrosion in compacted bentonite clay as a function of clay density and growth conditions for sulfate‐reducing bacteria

Aims: To investigate the relationships between sulfate‐reducing bacteria (SRB), growth conditions, bentonite densities and copper sulfide generation under circumstances relevant to underground, high‐level radioactive waste repositories. Methods and Results: Experiments took place 450 m underground, connected under in situ pressure to groundwater containing SRB. The microbial reduction of sulfate to sulfide and subsequent corrosion of copper test plates buried in compacted bentonite were analysed using radioactive sulfur (³⁵SO₄^2?) as tracer. Mass distribution of copper sulfide on the plates indicated a diffusive process. The relationship between average diffusion coefficients (D_s) and tested density (ρ) was linear. D_s (m² s^?1) = ?0·004 × ρ (kg m^?3) + 8·2, decreasing by 0·2 D_s units per 50 kg m^?3 increase in density, from 1·2 × 10^?11 m² s^?1 at 1750 kg m^?3 to 0·2 × 10^?11 m² s^?1 at 2000 kg m^?3. Conclusions: It is possible that sulfide corrosion of waste canisters in future radioactive waste repositories depends mainly on sulfide concentration at the boundary between groundwater and the buffer, which in turn depends on SRB growth conditions (e.g., sulfate accessibility, carbon availability and electron donors) and geochemical parameters (e.g., presence of ferrous iron, which immobilizes sulfide). Maintaining high bentonite density is also important in mitigating canister corrosion. Significance and Impact of the Study: The sulfide diffusion coefficients can be used in safety calculations regarding waste canister corrosion. The work supports findings that microbial activity in compacted bentonite will be restricted. The study emphasizes the importance of growth conditions for sulfate reduction at the groundwater boundary of the bentonite buffer and linked sulfide production.     

Ammonia removal from a waste air stream using a biotrickling filter packed with polyurethane foam through the SND process

This paper presents the results of a bench-scale biotrickling filter (BTF) on the removal of ammonia gas from a waste stream using a simultaneous nitrification/denitrification (SND) process. It was found that the developed BTF could completely remove 100 ppm ammonia from a waste stream, with an empty bed retention time of 60 s and 98.4% nitrogen removal through the SND process under the tested conditions. It was elucidated that both autotrophic and heterotrophic bacteria were involved in the nitrogen removal trough the SND process in the BTF. Additionally, the elimination capacity of total nitrogen by the BTF increased from 3.5 to 18.4 g N/m³ h with an inlet load of 20.6 g N/m³ h (73.6%). The findings of this study suggest that the BTF can be operated to attain complete ammonia removal through the SND process, thereby making the treatment of ammonia-laden gas streams both short and cost-effective.     

Utilization of iron sulfides for wastewater treatment: a critical review

Acid mine drainage due to weathering of iron sulfide minerals is one of the biggest global environmental issues. However, due to the unique physicochemical properties of natural and synthesized iron sulfides (i.e. pyrite, pyrrhotite, and mackinawite), they can be effectively used for wastewater treatment. These properties, such as ≡SH functional groups as Lewis bases, reducibility of surface Fe and S species, dissolved Fe²⁺ as a catalyst, and dissolved S^2? as an electron donor, are extensively reviewed in this article. The target water pollutants include toxic metals (i.e. lead, mercury, cadmium, and hexavalent chromium) and metalloid (i.e. arsenic), radionuclides (i.e. uranium and selenium), organic contaminants (i.e. chlorinated organic pollutants, benzene and polycyclic aromatic hydrocarbons), and nutrients (i.e. nitrogen and phosphorus). The dominant interaction mechanisms between iron sulfides and these contaminants, and the removal efficiencies are elucidated. This article focuses on the role of iron sulfides as functional materials for wastewater treatment. A recent development of nanostructured pyrrhotite with a high specific surface area for wastewater treatment is also highlighted.     

Direct labeling of proteins with 99mTc

The direct labeling of antibodies and antibody fragments to form a highly stable bond between technetium and the sulfide groups of proteins is now well established. To optimize this reaction, the antibody protein must have sufficient reactive sulfides available to accept that technetium metal ions that are formed by the reduction of pertechnetate in the presence of a weak complexing agent. The reactive sulfide groups are provided by first reducing a small fraction of the disulfide bridges in the antibody protein or by starting with Fab′ fragments, which already have reactive sulfide groups. When the antibody protein has been appropriately reduced, and the reactive sulfide groups protected by a metal ion with a lower binding affinity than technetium, such as tin or zinc, very high labeling yields of high-affinity-bonded ^99mTc can be achieved. This can be accomplished without loss of immunoreactivity, measured as either affinity or immunoreactive fraction.Side reactions can produce radiochemical impurities such as low-affinity, bound ^99mTc; ^99mTc colloids; ^99mTc peptides or antibody aggregates; or ^99mTc-complexes. Also, pertechnetate ions may be an impurity if the sodium pertechnetate solution added to the reduced antibodies is not completely reduced. The specifics of minimizing these side reactions have not been extensively discussed in the prior literature; however, it is clear that appropriate reduction of the protein prior to labeling and complete removal of the reducing agent, particularly if it contains reactive sulfide groups or is toxic, are critical.One- or two-step ^99mTc-labeling kits for preparing ^99mTc-labeled antibody or antibody fragments are rapidly being introduced for use in clinical nuclear medicine studies. These direct labeling methods employ a common sequence of chemical reactions, although the reducing agents for both the antibody and the [^99mTc]pertechnetate may vary. Different ^99mTc transfer agents may be used, but all transfer agents have the common feature of quickly forming weak to moderately strong complexes with reduced technetium. Most use Sn(II) to reduce the pertechnetate, although other reducing agents can be used.     

Application of biofiltration to the degradation of hydrogen sulfide in gas effluents

A laboratory scale bioreactor has been designed and set up in order to degrade hydrogen sulfide from an air stream. The reactor is a vertical column of 7 litre capacity and 1 meter in height. It is divided into three modules and each module is filled with pellets of agricultural residues as packing bed material. The gas stream fed into the reactor through the upper inlet consists of a mixture of hydrogen sulfide and humidified air. The hydrogen sulfide content in the inlet gas stream was increased in stages until the degradation efficiency was below 90%. The parameters to be controlled in order to reach continuous and stable operation were temperature, moisture content and the percentage of the compound to be degraded at the inlet and outlet gas streams (removal or elimination efficiency). When the H₂S mass loading rate was between 10 and 40 g m^-3h^-1, the removal efficiency was greater than 90%. The support material had a good physical performance throughout operation time, which is evidence that this material is suitable for biofiltration purposes.     

A field investigation of the relationship between zinc and acid volatile sulfide concentrations in freshwater sediments

Understanding relationships between cationic metals such as cadmium, copper, nickel, lead and zinc, and amorphous iron sulfides, measured as acid volatile sulfide (AVS), is key to predicting metal bioavailability and toxicity insediments. The objective of the present study was to assess seasonal and spatial variations of AVS in freshwater sediments contaminated with zinc. Sediments were sampled from three streams with varying levels of zinc contamination at two different times, March and June of 1995, representing cold- and warm-weather situations. Interstitial (pore) water concentrations of zinc, and solid phase concentrations of AVS and zinc were measured in surficial and deep sediment horizons. Toxicity tests (10-d) with the amphipodHyalella azteca were conducted using intact cores. Sediment zinc concentrations from six sites within the primary test stream differed by about five-fold, and also varied seasonally. Acid volatile sulfide concentrations were generally lower than those of zinc, and pore water zinc concentrations typically were elevated. There was a positive correlation between solid-phase AVS and zinc concentrations, suggesting that the system was dominated by zinc, as opposed to iron sulfides. In contrast to expectations arising from some studies of seasonal variations of AVS in iron-dominated systems, AVS concentrations were smaller in June than in March. However, this was likely due to a major storm event and associated sediment scouring before the June sampling, rather than to seasonal processes related to variations in temperature and dissolved oxygen. Based upon an indirect analysis of depth variations in AVS, there was some indication that zinc sulfide might be less prone to oxidation than iron sulfide. There was a strong correlation between toxicity of the sediment samples toH. azteca and interstitial water concentrations of zinc; however, the possible contribution of other contaminants to sediment toxicity cannot be dismissed.     

Impacts of reduced sulfur components on active and resting ammonia oxidizers

While there has been significant research on the nature and extent of the impact of inhibitory reduced sulfur with respect to anaerobic (e.g., methanogenic and sulfidogenic) microbial systems, only limited study has yet been conducted on the comparable effects of soluble sulfides which might occur within aerobic wastewater treatment systems. Admittedly, aerobic reactors would not normally be considered conducive to the presence of reduced sulfur constituents, but there do appear to be a number of processing scenarios under which related impacts could develop, particularly for sensitive reactions like nitrification. Indeed, the following scenarios might well involve elevated levels of reduced sulfur within an aerobic reactor environment: (1) mixed liquor recycle back through sulfide-generating anaerobic zones (e.g., in conjunction with biological nutrient removal processes, etc.), (2) high-level side-stream sulfide recycle via sludge digestion, etc., back to aerobic reactors, and (3) high-level influent sulfide inputs to wastewater treatment facilities via specific industrial, septage, etc., streams. The objective of this study was, therefore, to determine the subsequent metabolic impact of soluble sulfide under aerated and unaerated conditions, focusing in particular on ammonia-oxidizing bacteria due to their critical first-step role with nitrification. The obtained results indicated that, under catabolically active conditions, cultures of ammonia oxidizers were extremely sensitive to the presence of sulfide. At total soluble sulfide concentrations of 0.25 mg l^–1 S, active ammonia oxidation was completely inhibited. However, immediately following the removal of this soluble sulfide presence, ammonia oxidation started to recover; and it continued to improve over the next 24 h. Similar sulfide impact tests conducted with inactive ammonia oxidizers exposed during anaerobic conditions, albeit at higher dosage levels, also revealed that their subsequent aerobic activity would correspondingly be retarded. These results indicated that, after sulfide exposure under unaerated conditions, subsequent aerobic oxidative activity rates rapidly decreased as the soluble sulfide exposure was increased from 0.5 gm l^–1 S to 5 mg l^–1 S and that further reductions in this activity progressively developed as the concentration was increased to 200 mg l^–1 S. The recovery following unaerated exposure to sulfide was significantly higher at pH 7, as compared with pH 8, and although the specific nature of this variation was not established, a hypothetical explanation appeared warranted.     

The pilot study for waste oil removal from oilfields by <Emphasis Type="Italic">Acinetobacter johnsonii</Emphasis> using a specialized batch bioreactor

The batch bioreactor with a maximum capacity of 0.28 m³ was designed and manufactured according to oilfield conditions Acinetobacter johnsonii ioslated from waste oil in an aerobic environment was employed to cleanse waste oil and wash-down water using the bioreactor in a pilot scale. The aerating process was optimized from 2 to 4 m³/h corresponding to the different cell growth phases, ensuring sufficient dissolved oxygen and avoiding cell damage from the shearing forces due to strong aeration. The bio-treatment of waste oil underwent two stages:one was the wettability reversal of inorganic admixtures from oil phase into waster phase through enlarged wetting angles, and the other was the bio-flocculation in waster phase by intermediate metabolites excreted by cells. Finally, inorganic admixtures were effectively removed from waste oil and wash-down water at the optimal conditions, with the content less than 0.5% in oil phase and turbidity and sulfide less than 100 NTU and 1 mg/L in the water phase, respectively. Such bio-treatment made the oil-water interface clear against oil and water emulsification and in favor of smooth reclamations for waste oil and wash-down water.     

Complete genome sequence of "Thioalkalivibrio sulfidophilus" HL-EbGr7

"Thioalkalivibrio sulfidophilus" HL-EbGr7 is an obligately chemolithoautotrophic, haloalkaliphilic sulfur-oxidizing bacterium (SOB) belonging to the Gammaproteobacteria. The strain was found to predominate a full-scale bioreactor, removing sulfide from biogas. Here we report the complete genome sequence of strain HL-EbGr7 and its annotation. The genome was sequenced within the Joint Genome Institute Community Sequencing Program, because of its relevance to the sustainable removal of sulfide from bio- and industrial waste gases.     

Effects of stocking density and feeding rate on vermicomposting of biosolids

The double-pronged problem of quantity, and disposal of waste streams from a myriad of industries, is becoming increasingly acute, the world over. The use of earthworms as a waste treatment technique for such wastes is gaining popularity. This method is commonly known as vermicomposting. Compared to conventional microbial composting, vermicomposting produces a product that is more or less homogenous, with desirable aesthetics, with reduced levels of contaminants and tends to hold more nutrients over a longer period, without impacting the environment. Like in other related waste treatment techniques, certain parameters need to be established for the design of efficient and economical vermicomposting systems. Specifically, the focus of this study was to investigate and establish an optimal stocking density and an optimal feeding rate for the vermicomposting of biosolids, with paper mulch provided as bedding. A stocking density of 1.60 kg-worms/m² (0.33 lb-worms/ft²) and a feeding rate of 1.25 kg-feed/kg-worm/day resulted in the highest bioconversion of the substrate into earthworm biomass. The best vermicompost was obtained at the same stocking density and a feeding rate of 0.75 kg-feed/kg-worm/day.     

Sulfur accumulation in eelgrass (Zostera marina) and effect of sulfur on eelgrass growth

Eelgrass (Zostera marina) was grown under exposure to high levels of sediment sulfides to examine their ability to reoxidize sulfides intruding into the plants. The plants were kept under full light (control and high sulfide level) and at 10% of light saturation (high sulfide level) for 3 weeks and growth and accumulation of elemental sulfur (S⁰) in the plants were examined. The growth rate was reduced with ∼75% in the low light treatment, whereas there was no significant difference between the rates at full light saturation. S⁰ was accumulating in the below-ground structures of the plants exposed to high sulfide concentrations with highest concentration in the youngest roots and oldest internodes. There was no accumulation of S⁰ in the leaves, suggesting that the intruding sulfides were reoxidized in the below-ground structures before reaching the leaves. The accumulation of S⁰ was higher in the roots of the low light treatment (up to two times) suggesting a larger intrusion of sulfides. These plants also appeared highly affected by the treatment with rotting meristems and increased mortality after the 3-week growth period. These results are the first to show an accumulation of sulfur compounds internally in seagrasses as a result of reoxidation of sulfides. The reoxidation is facilitated by the internal transport of oxygen and is an example of the advantage of the internal lacunae system in seagrasses.     

Continuous anaerobic treatment of wastewater from a kraft pulp mill

A pilot-scale study of the thermophilic anaerobic digestion of high-strength wastewater (evaporator condensate, EC) discharged from a kraft pulp production process was performed. The system consisted of a microfiltration (MF) membrane module for oily substances removal, a stripping system using evolved gas from the digester for sulfur compounds removal, an anaerobic fixed-bed bioreactor for methane fermentation, and an ultrafiltration (UF) membrane module for retention of a high density of bacterial cells. The bioreactor had a fixed-bed with an effective volume of 5 m³ packed with pumice stone. In a continuous run with only the MF membrane module for oily substances removal, the digester efficiency declined because of methanogenic inhibition by sulfur compounds. After fitting of the stripping system which used evolved gas from the digester, the inhibitive sulfur compounds in the EC were removed more than 80%, and high-loading and high-efficiency operation could be attained. The BOD loading and BOD removal of 35.5 kg BOD/m³/d and 93%, respectively were attained. By anaerobic treatment of the evaporator condensate waste before the conventional aerobic activated sludge method, the total costs would be reduced to ¥3.31/m³ wastewater compared with ¥4.53/m³-wastewater by the aerobic activated sludge method only. The stability of digester performance against interruption by feed stoppage was also examined.     

Aerobic biotransformation of 4-fluorocinnamic acid to 4-fluorobenzoic acid

The biotransformation of 4-fluorocinnamic acid (FCA) using non-acclimated industrial activated sludge was investigated. FCA is a common intermediate in organic synthesis, and it is often present in aqueous waste streams. Hence, the biotransformation reactions this compound undergoes when exposed to activated sludge micro-organisms should be understood before waste streams are sent to biological wastewater treatment plants (WWTPs). FCA biotransformation was monitored using a wide range of analytical techniques. These techniques were used to monitor not only FCA disappearance, but also the formation of degradation products, in order to propose the metabolic pathway. FCA was biotransformed to 4-fluorobenzoic acid via the formation of 4-fluoroacetophenone. The removal of FCA up to 200 mg L^-1 followed first order kinetics. The half-lives for removal of FCA from the test solutions supplied with 200 mg L^-1, 100 mg L^-1, and 50 mg L^-1 were 53, 18, and 5 hours respectively.     

Abatement of volatile organic sulfur compounds in odorous emissions from the bio-industry

Compounds of interest in this work are methanethiol (MeSH), dimethyl sulfide (Me₂S), dimethyl polysulfides (Me₂S_x) and carbon disulfide (CS₂) since these volatiles have been identified as predominant odorants in the emission of a wide range of activities in the bio-industry (e.g. aerobic waste water treatment plants, composting plants, rendering plants). In these processes, the occurrence of volatile organic sulfur compounds is mainly related to the presence of anaerobic microsites with consecutive fermentation of sulfur containing organic material and/or to the breakdown of the latter due to thermal heating. Due to the chemical complexity of these low-concentrated waste gas streams and the high flow rates to be handled, mainly biotechnological techniques and scrubbers can be used to control the odour emission. When using biofilters or trickling filters, inoculation with specific micro-organisms and pH-control strategies should be implemented to optimise the removal of volatile organic sulfur compounds. In scrubbers, chemical oxidation of the volatile organic sulfur compounds can be obtained by dosing hypochlorite, ozone or hydrogen peroxide to the scrubbing liquid. However, optimal operational conditions for each of these abatement techniques requires a further research in order to guarantee a long-term and efficient overall odour abatement.     

Sulfur cycling and seagrass (Posidonia oceanica) status in carbonate sediments

Sulfur cycling was investigated in carbonate-rich and iron-poor sediments vegetated with Posidonia oceanica in oligotrophic Mediterranean around Mallorca Island, Spain, to quantify sulfate reduction and pools of sulfide in seagrass sediments. The oxygen penetration depth was low (< 4.5 mm) and sulfate reduction rates were relatively high (0.7–12 mmol m^–2d^–1). The total pools of reduced sulfides were remarkably low (< 5 mol S m^–2) indicating a fast turnover of reduced sulfides in these iron-poor sediments. The sulfate reduction rates were generally higher in vegetated compared to bare sediments possible due to enhanced sedimentation of sestonic material inside the seagrass meadows. The sulfate reduction rates were positively correlated with the seasonal variation in water temperature and negatively correlated with the shoot density indicating that the microbial activity was controlled by temperature and release of oxygen from the roots. The pools of reduced sulfides were low in these iron-poor sediments leading to high oxygen consumption for reoxidation. The sediments were highly anoxic as shown by relatively low oxygen penetration depths (< 4.5 mm) in these low organic sediments. The net shoot recruitment rate was negative in sediments enriched with organic matter, suggesting that organic matter enrichment may be an important factor for seagrass status in these iron-depleted carbonate sediments.     

Performance study of biofilter developed to treat H2S from wastewater odour

Biofiltration is an efficient biotechnological process used for waste gas abatement in various industrial processes. It offers low operating and capital costs and produces minimal secondary waste streams. The objective of this study was to evaluate the performance of a pilot scale biofilter in terms of pollutants’ removal efficiencies and the bacterial dynamics under different inlet concentrations of H₂S. The treatment of odourous pollutants by biofiltration was investigated at a municipal wastewater treatment plant (WWTP) (Charguia, Tunis, Tunisia). Sampling and analyses were conducted for 150 days. Inlet H₂S concentration recorded was between 200 and 1300 mg H₂S.m⁻³. Removal efficiencies reached 99% for the majority of the running time at an empty bed retention time (EBRT) of 60 s. Heterotrophic bacteria were found to be the dominant microorganisms in the biofilter. The bacteria were identified as the members of the genus Bacillus, Pseudomonas and xanthomonadacea bacterium. The polymerase chain reaction-single stranded conformation polymorphism (PCR-SSCP) method showed that bacterial community profiles changed with the H₂S inlet concentration. Our results indicated that the biofilter system, containing peat as the packing material, was proved able to remove H₂S from the WWTP odourous pollutants.     

Recycling of lipid-extracted hydrolysate as nitrogen supplementation for production of thraustochytrid biomass

Efficient resource usage is important for cost-effective microalgae production, where the incorporation of waste streams and recycled water into the process has great potential. This study builds upon emerging research on nutrient recycling in thraustochytrid production, where waste streams are recovered after lipid extraction and recycled into future cultures. This research investigates the nitrogen flux of recycled hydrolysate derived from enzymatic lipid extraction of thraustochytrid biomass. Results indicated the proteinaceous content of the recycled hydrolysate can offset the need to supply fresh nitrogen in a secondary culture, without detrimental impact upon the produced biomass. The treatment employing the recycled hydrolysate with no nitrogen addition accumulated 14.86 g L^?1 of biomass in 141 h with 43.3 % (w/w) lipid content compared to the control which had 9.26 g L^?1 and 46.9 % (w/w), respectively. This improved nutrient efficiency and wastewater recovery represents considerable potential for enhanced resource efficiency of commercial thraustochytrid production.     

Biological decomposition of dichloromethane from a chemical process effluent

The application of specialized microorganisms to treat dichloromethane (DM) containing process effluents was studied. An aerobic fluidized bed reactor with a working volume of 801 filled with sand particles as carriers for the bacteria was used. Oxygen was introduced into the recycle stream by an injector device. DM was monitored semi-continuously. A processor controlled the feed volume according to the DM effluent concentration. Mineralization rates of 12 kg DM/m_bioreactor ³ · d were reached within about three weeks using synthetic wastewater containing 2000 mg/l DM as single carbon compound. DM from process water of a pharmaceutical plant was reduced from about 2000 mg/l in the feed to below 1 mg/l in the effluent at volumetric loading rates of 3 to 4 kg DM/m_bioreactor ³ · d. Degradation of wastewater components like acetone and isopropanol were favoured, thus making the process less attractive for waste streams containing high amounts of DOC other than of DM. DM concentrations of up to 1000 mg/l were tolerated by the immobilized microorganisms and did not influence their DM degradation capacity. The ability to mineralize DM was lost when no DM was fed to the reactor for 10 days.