Biological treatment of gaseous emissions containing dimethyl sulphide generated from pulp and paper industry

A critical review on characterization, human health risk assessment and mitigation of malodorous gaseous emission during the composting process

Composting has emerged as a suitable method to convert or transform organic waste including manure, green waste, and food waste into valuable products with several advantages, such as high efficiency, cost feasibility, and being environmentally friendly. However, volatile organic compounds (VOCs), mainly malodorous gases, are the major concern and challenges to overcome in facilitating composting. Ammonia (NH3) and volatile sulfur compounds (VSCs), including hydrogen sulfide (H2S), and methyl mercaptan (CH4S), primarily contributed to the malodorous gases emission during the entire composting process due to their low olfactory threshold. These compounds are mainly emitted at the thermophilic phase, accounting for over 70% of total gas emissions during the whole process, whereas methane (CH4) and nitrous oxide (N2O) are commonly detected during the mesophilic and cooling phases. Therefore, the human health risk assessment of malodorous gases using various indexes such as ECi (maximum exposure concentration for an individual volatile compound EC), HR (non-carcinogenic risk), and CR (carcinogenic risk) has been evaluated and discussed. Also, several strategies such as maintaining optimal operating conditions, and adding bulking agents and additives (e.g., biochar and zeolite) to reduce malodorous emissions have been pointed out and highlighted. Biochar has specific adsorption properties such as high surface area and high porosity and contains various functional groups that can adsorb up to 60%-70% of malodorous gases emitted from composting. Notably, biofiltration emerged as a resilient and cost-effective technique, achieving up to 90% reduction in malodorous gases at the end-of-pipe. This study offers a comprehensive insight into the characterization of malodorous emissions during composting. Additionally, it emphasizes the need to address these issues on a larger scale and provides a promising outlook for future research.

Simultaneous biodegradation of dimethyl sulfide and 1-propanethiol by Pseudomonas putida S-1 and Alcaligenes sp. SY1: "Lag" cause, reduction, and kinetics exploration

Simultaneous biodegradation of malodorous 1-propanethiol (PT) and dimethyl sulfide (DMS) by Pseudomonas putida S-1 and Alcaligenes sp. SY1 was investigated and the interactions implicated were explored. Results showed that PT was completely degraded in 33 h, while a lag of 10 h was observed for DMS degradation alone, and the lag was even extended to 81 h in the binary mixture. Mechanism analysis found that the lag was mainly attributed to the exposure of DMS degrader (Alcaligenes sp. SY1), rather than PT metabolites and PT degrader. The exposure time and PT concentration also influenced the lag duration much. Citric acid could effectively reduce the lag. Pseudo-first-order model was proved suitable for the description of PT degradation, revealing that PT degradation could be enhanced in presence of DMS with a concentration of < 50 mg L-1. A modified Gompertz model, incorporated the lag phase, was developed for the description of DMS degradation in the mixture, revealing that DMS degradation depended on the initial PT concentration, and when the lag was not considered, PT with low-concentration could promote DMS biodegradation, while a higher concentration (> 20 mg L-1) cast negative effect.

Development of a feedback control system for a differential biofilter degrading toluene contaminated air

In this study, a proportional - integral feedback control system was implemented on a lab-scale differential biofilter to control the gas phase toluene concentration in the soil bed through online manipulation of the inlet toluene concentration. The feedback control system was based on a cascade controller that manipulated the setpoint of an air bath diffusion system to manipulate the inlet toluene concentration. The controller performed well for toluene concentrations in the reactor of 10 - 300 ppm for both setpoint changes and disturbance rejections; however, the system was nonlinear requiring different tuning parameters at different outlet concentrations. Feedback control of the toluene concentration in the differential reactor was used to explore the impact of concentration on start-up and long-term biofilter operation in a rigorous fashion. Starting at an reactor concentration of 20 ppm and then increasing to 65 ppm increased the toluene removal rate (33 ± 1.6 g m^-3h^-1) compared to starting the reactor at an outlet concentration of 81 ppm before settling at 65 ppm (42 ± 0.9 g m^{- 3}h^-1). The toluene removal rate increased with increasing outlet toluene concentration and then eventually decreased when reaching the inhibitory toluene concentration (ranged from 80 to 250 ppm).

Enhancement of using combined packing materials on the removal of mixed sulfur compounds in a biotrickling filter and analysis of microbial communities

Background

Packing materials is a critical design consideration when employing biological reactor to treat malodorous gases. The acidification of packing bed usually results in a significant drop in the removal efficiency. In the present study, a biotrickling filter (BTF2) packed with plastic balls in the upper layer and with lava rocks in the bottom layer, was proposed to mitigate the acidification.

Results

Results showed that using combined packing materials efficiently enhanced the removal performance of BTF2 when compared with BTF1, which was packed with sole lava rocks. Removal efficiencies of more than 92.5% on four sulfur compounds were achieved in BTF2. Average pH value in its bottom packing bed was about 4.86, significantly higher than that in BTF1 (2.85). Sulfate and elemental sulfur were observed to accumulate more in BTF1 than in BTF2. Analysis of principal coordinate analysis proved that structure of microbial communities in BTF2 changed less after the shutdown but more when the initial pH value was set at 5.5. Network analysis of significant co-occurrence patterns based on the correlations between microbial taxa revealed that BTF2 harbored more diverse microorganisms involving in the bio-oxidation of sulfur compounds and had more complex interactions between microbial species.

Conclusions

Results confirmed that using combined packing materials effectively improved conditions for the growth of microorganisms. The robustness of reactor against acidification, adverse temperature and gas supply shutdown was greatly enhanced. These provided a theoretical basis for using mixed packing materials to improve removal performance.

Removal of hydrogen sulfide generated during anaerobic treatment of sulfate-laden wastewater using biochar: Evaluation of efficiency and mechanisms

Removal of hydrogen sulfide (H₂S) from biogas was investigated in a biochar column integrated with a bench-scale continuous-stirred tank reactor (CSTR) treating sulfate-laden wastewater. Synthetic wastewater containing sulfate concentrations of 200-2000mg SO₄^2-/L was used as substrate, and the CSTR was operated at an organic loading rate of 1.5g chemical oxygen demand (COD)/L·day and a hydraulic retention time (HRT) of 20days. The biochar was able to remove about 98.0 (±1.2)% of H₂S for the ranges of concentrations from 105-1020ppmv, especially at high moisture content (80-85%). Very high H₂S adsorption capacity (up to 273.2±1.9mg H₂S/g) of biochar is expected to enhance the H₂S oxidation into S⁰ and sulfate. These findings bring a potentially novel application of sulfur-rich biochar as a source of sulfur, an essential but often deficient micro-nutrient in soils.

Performance evaluation of Malathion biodegradation in batch and continuous packed bed bioreactor (PBBR)

The aim of this work was to study the biodegradation of Malathion in batch and continuous packed bed (Polyurethane foam; PUF) bioreactor (PBBR). After 10days, 89% Malathion removal was observed in batch PBBR. Continuous PBBR was operated at various flow rates (5-30mL/h) under optimum condition over a period of 75days. Inlet loading rates and elimination capacities were observed in the range of 36-216 and 7.20-145.4mg/L/day with an average removal efficiency of more than 90% under steady state conditions. GC/MS analysis confirms phosphorodithionicacid,O,O,S-trimethylester and diethylmercaptosuccinate as metabolites. Biodegradation of Malathion under inhibitory and non-inhibitory conditions was studied using Monod and Andrew-Haldane models and the kinetic constants were calculated and found to be μ_max: 0.271 per day; K_s: 126.3mg/L using Monod and μ_max: 0.315 per day; K_s: 151.32mg/L; K_i: 594.75mg/L using Andrew-Haldane models.

Biofilms formed within the acidic and the neutral biotrickling filters for treating H2S-containing waste gases

Microbial cell in the innermost biofilm have higher viability, and produce polysaccharide as the main component of EPS in acidic environment.

Control of dimethyl sulfide and dimethyl disulfide odors during pig manure composting using nitrogen amendment

Effects of nitrogen electron acceptors on dimethyl sulfide (Me₂S) and dimethyl disulfide (Me₂SS) odor emission during composting was investigated. The chemicals and doses used included sodium nitrate (NO₃^- at 10mM, 20mM and 40mM), sodium nitrite (NO₂^- at 10mM, 20mM and 40mM) and sodium nitrite (10mM, 20mM and 40mM) with hexaammonium heptamolybdate tetrahydrate (HHT). The results showed that the addition of these chemicals restricted the emission of Me₂S and Me₂SS. The emission reduction effect of NO₂^- was greater than NO₃^- at the same dosage. A greater reduction was observed when HHT was also added. With 2mM HHT+40mM NO₂^- addition, the emission of Me₂S and Me₂SS was reduced by 92.3% and 82.3%, respectively. Comparison of compost maturity indices for treated and untreated composts indicated that none of the additives adversely affected compost quality. These results indicate that nitrogen chemical addition may provide an efficient method to control sulfur odors during composting.

Mixed Cu(i)/Au(i) coordination polymers as reversible turn-on vapoluminescent sensors for volatile thioethers

Cu(i)-doping transforms an inactive Cu(i)/Au(i) coordination polymer into an emissive, reversible solid state sensor for dimethyl- and diethyl sulphide.

Sulfides Synthesis: Nanocatalysts in C–S Cross-Coupling Reactions

The C–S cross-coupling reaction of aryl halides with thiols or sulfur sources is a key and valuable synthetic transformation in chemistry and medicine as well as in biology, and the development of novel efficient synthetic protocols for the synthesis of the corresponding products (sulfides) is highly desired. Among a wide range of catalysts used in C–S coupling reactions, metallic nanocatalysts have attracted notable interest. Herein, we summarize recent breakthroughs in the arena of metal nanocatalysts employed in C–S cross-coupling reactions with the goal of stimulating further progress in this field. This review is divided into three main sections according to the nature of the metal nanocatalysts discussed. The first section focuses on naked or purely metallic catalysts in nano-size, such as Cu, Pd, Ni, and In. The second section focuses on the role of Fe3O4 magnetic nanoparticles and mesoporous silica nanomaterials, such as MCM-41 and SBA-15, as catalyst supports. Finally, the third section focuses on the catalytic activities of copper ferrite nanoparticles in C–S cross-coupling reactions. Additionally, the recovery and reusability of the nanocatalyst, which are very important from commercial and economical points of view, are comprehensively discussed in this review.

Air pollution control through biotrickling filters: a review considering operational aspects and expected performance

The biological removal of pollutants, especially through biotrickling filters (BTFs), has recently become attractive for the low investment and operational costs and the low secondary pollution. This paper is intended to investigate the state of the art on BTF applications. After an overview on the biodegradation process and the typical parameters involved, this paper presents the analysis of a group of 16 literature studies chosen as the references for this sector. The reference studies differ from one another by the pollutants treated (volatile organic compounds [VOC], hydrogen sulphide, nitrogen oxides and trimethylamine), the geometry and size of the BTFs, and the procedures of the tests. The reference studies are analyzed and discussed in terms of the operational conditions and the results obtained, especially with respect to the removal efficiencies (REs) and the elimination capacities (ECs) of the pollutants considered. Empty bed residence time (EBRT), pollutant loading rate, temperature, pH, oxygen availability, trickling liquid flow rate, inoculum selection and biomass control strategies revealed to be the most important operational factors influencing the removal performance of a BTF.

Aerobic biodegradation of odorous dimethyl disulfide in aqueous medium by isolated Bacillus cereus GIGAN2 and identification of transformation intermediates

A novel, flagellated, rod-shape, Gram-positive facultative aerobe, was isolated and identified as Bacillus cereus GIGAN2. It can effectively remove model odorous organics dimethyl disulfide (DMDS) in aqueous solution under aerobic conditions. Initial concentration, pH value and temperature played important role in DMDS biodegradation, and up to 100% of 10mgL(-1) of DMDS could be removed within 96h under the optimum conditions (30°C, pH 7.0 and 200rpm) with a maximum biodegradation rate constant of 0.0330h(-1) and minimum half-life of 21.0h, respectively. Three main intermediates were identified using gas chromatography-mass spectrometry during this biodegradation process. Further, a reaction scheme is also proposed to explain the possible DMDS biodegradation mechanism by GIGAN2 based on the above-identified intermediates. Overall, this is the first report to demonstrate a newly isolated strain using high concentrated DMDS as the sole carbon and energy source with high efficiency.

Removal of dimethyl sulfide by the combination of non-thermal plasma and biological process

A bench scale system integrated with a non-thermal plasma (NTP) and a biotricking filtration (BTF) unit for the treatment of gases containing dimethyl sulfide (DMS) was investigated. DMS removal efficiency in the integrated system was up to 96%. Bacterial communities in the BTF were assessed by PCR-DGGE, which play the dominant role in the biological processes of metabolism, sulfur oxidation, sulfate-reducing and carbon oxidation. The addition of ozone from NTP made microbial community in BTF more complicated and active for DMS removal. The NTP oxidize DMS to simple compounds such as methanol and carbonyl sulfide; the intermediate organic products and DMS are further oxidized to sulfate, carbon dioxide, water vapors by biological degradation. These results show that NTP-BTF is achievable and open new possibilities for applying the integrated with NTP and BTF to odour gas treatment.