Comparison and application of biofilter and suspended bioreactor in removing gaseous o-xylene

Bio-enriched composite materials derived from waste cooking oil for selective reduction of odour intensity

Currently, pathogenic microorganisms are becoming more active in public utility areas like parking lots and waste shelters due to the accumulation of organic waste. This uncontrolled waste leads to decay, altering its composition and presenting a microbiological risk to public health. Additionally, it emits unpleasant odors containing chemicals that irritate the mucous membranes, causing discomfort in the nose, throat, and eyes by stimulating the trigeminal nerve. These odors can have various negative effects on both quality of life and public health. The study investigated the physicochemical properties of oil composites enriched with natural additives and determined their effectiveness in reducing the intensity of nuisance odours. The research showed over 82% reduction in decaying meat odour and almost 65% reduction in ammonia odour. A higher impact of the given composites on reducing the odour from decaying meat than from ammonia was observed. This may be due to the biocidal properties of the additives used (turmeric, thymol, salicylic acid, hops and curly sorrel) and the higher intensity of ammonia odor compared to meat-derived odour. Despite the non-porous nature of the solids tested (with similar specific surface areas ranging from 0.66 to 0.88 m2/g), they were capable of sorbing NH3.

Evaluation of packing materials for thermophilic biofilter by refined evaluation scheme and application in the treatment of SO2 with high temperature

The selection of packing materials is essential to maintaining biofilter performance in waste gas treatment. In this study, 12 types of packing materials were evaluated to determine the most suitable for the SO2 removal by a thermophilic biofilter. Scanning electron microscopy and the Baunauer-Emmett-Teller equation were utilized to identify the texture of the tested packing materials, while Fourier transform infrared spectroscopy and X-ray diffraction were applied to analyze the surface functional groups and crystal structures, respectively. Characteristics were accompanied by economic considerations. Results showed that the polyurethane sponge had better porous structure and water retention than other packing materials. In terms of microbial growth and carrier economy, it was chosen for the biofilter used to treat SO2. The performance of a full-scale thermophilic biofilter with polyurethane sponge as the packing material was investigated for the purification of SO2-containing gases at an inlet temperature of 55 °C. The biofilter effectively removed SO2 at an average removal rate of 93.36%. Thermophilic bacteria and sulfur-oxidizing bacteria, e.g., Bacillus thermophilus, could attached growth on the surface of selected packing materials and exhibited degradation activity. This study provides an effective and feasible method of packing material selection for biological waste gas treatment.

A review of the recent progress in biotrickling filters: packing materials, gases, micro-organisms, and CFD

Organic pollutants in the air have serious consequences on both human health and the environment. Among the various methods for removing organic pollution gas, biotrickling filters (BTFs) are becoming more and more popular due to their cost-effective advantages. BTF can effectively degrade organic pollutants without producing secondary pollutants. In the current research on the removal of organic pollutants by BTF, improving the performance of BTF has always been a research hotspot. Researchers have conducted studies from different aspects to improve the removal performance of BTF for organic pollutants. Including research on the performance of BTF using different packing materials, research on the removal of various mixed pollutant gases by BTF, research on microbial communities in BTF, and other studies that can improve the performance of BTF. Moreover, computational fluid dynamics (CFD) was introduced to study the microscopic process of BTF removal of organic pollutants. CFD is a simulation tool widely used in aerospace, automotive, and industrial production. In the study of BTF removal of organic pollutants, CFD can simulate the fluid movement, mass transfer process, and biodegradation process in BTF in a visual way. This review will summarize the development of BTFs from four aspects: packing materials, mixed gases, micro-organisms, and CFD, in order to provide a reference and direction for the future optimization of BTFs.

Enhanced removal organic compounds and particles from cooking fume using activated sludge scrubber filled loofah: From performance to the mechanism

The catering industry's growth has resulted in cooking fume pollution becoming a major concern in people's lives. As a result, its removal has become a core research focus. Natural loofah is an ideal biofilm carrier, providing a conducive environment for microorganisms to grow. This study utilized natural loofah to fill domesticated activated sludge in a bioscrubber, forming biofilms that enhance the ability to purify cooking fume. This study found that the biomass of loofah biofilms per gram is 104.56 mg. The research also determined the removal efficiencies for oils, Non-methane total hydrocarbons (NMHC), PM2.5, and PM10 from cooking fumes, which were 91.53%, 67.53%, 75.25%, and 82.23%, respectively. The maximum elimination capacity for cooking fumes was found to be 20.7 g/(m3·h). Additionally, the study determined the kinetic parameters for the biodegradation of oils (Kc and Vmax) to be 4.69 mg L-1 and 0.026 h-1, respectively, while the enzyme activities of lipase and catalase stabilized at 75.50 U/mgprots and 67.95 U/mgprots. The microbial consortium identified in the biofilms belonged to the phylum Proteobacteria and consisted mainly of Sphingomonas, Mycobacterium, and Lactobacillus, among others.

Escape and functional alterations of microbial aerosol particles containing Pseudomonas sp. during wastewater treatment

Wastewater treatment plants (WWTP) are considered sources of bioaerosols emission that negatively affects the surrounding atmosphere. This study focused on Pseudomonas sp. Emissions in bioaerosols from a WWTP that adopts the A²O treatment process, and their inactivation through ultraviolet (UV) radiation. High-throughput sequencing was used to assay the microbial population, and functional composition profiles were predicted using 16 S rRNA sequencing data with PICRUSt2. Recorded emission levels of airborne bacteria and Pseudomonas sp. In WWTP were 130 ± 83-6113 ± 3015 CFU/m³ and 0-6431 ± 1945 CFU/m³, respectively. Bioaerosol emissions presented site-related and temporal variation. Over 80% of Pseudomonas sp. Were attached to coarse particles with sizes over 2.1 μm. Bioaerosol concentration and particle-size distribution in the air were closely related to ambient temperature, relative humidity, light intensity, and wind speed. Exposure to 45.67 μW/cm³ UV radiation led to a significant decline in bioaerosol concentrations in the air, and reduction rate reached 89.16% and 95.77% for airborne bacteria and Pseudomonas sp., respectively. The results suggested that UV radiation can be an effective method in reducing bioaerosols. Compared with other bacteria, Pseudomonas stutzeri and Bacillus sp. Are more resistant to UV radiation. The abundance of antibiotic resistance genes noticeably receded when exposed to UV irradiation. The relative abundance of cationic antimicrobial peptide resistance, categorized under human diseases in KEGG (level 3), significantly decreased in Pseudomonas sp. After 120 min of UV irradiation. This study provides a novel insight into the control of bioaerosol emissions carrying pathogenic bacteria.

Effects of Water Content and Irrigation of Packing Materials on the Performance of Biofilters and Biotrickling Filters: A Review

Biofilters (BFs) and biotrickling filters (BTFs) are two types of bioreactors used for treatment of volatile organic compounds (VOCs). Both BFs and BTFs use packing materials in which various microorganisms are immobilised. The water phase in BFs is stationary and used to maintain the humidity of packing materials, while BTFs have a mobile liquid phase. Optimisation of irrigation of packing materials is crucial for effective performance of BFs and BTFs. A literature review is presented on the influence of water content of packing materials on the biofiltration efficiency of various pollutants. Different configurations of BFs and BTFs and their influence on moisture distribution in packing materials were discussed. The review also presents various packing materials and their irrigation control strategies applied in recent biofiltration studies. The sources of this review included recent research articles from scientific journals and several review articles discussing BFs and BTFs.

Mass transfer and reaction simultaneously enhanced airlift microbial electrolytic cell system with high gaseous o-xylene removal capacity

To overcome the limitation of mass transfer and reaction rate involved in the biodegradation of gaseous o-xylene, the airlift reactor and microbial electrolysis cell were integrated to construct an airlift microbial electrolysis cell (AL-MEC) system for the first time, in which the bioanode was modified by polypyrrole to further improve biofilm attachment. The developed AL-MEC system achieved 95.4% o-xylene removal efficiency at optimized conditions, and maintained around 75% removal efficiency even while the inlet o-xylene load was as high as 684 g m^-3 h^-1. The existence of O₂ exhibited a competition in electrons with the bioanode but a positive effect on ring-opening process in the o-xylene oxidation. The limitation of mass transfer had been overcome as the empty bed resistance time in the range of 20-80 s did not influence the system performance significantly. The microbial community analysis confirmed the o-xylene degradation microbes and electroactive bacteria were the dominant, which could be further enriched at 0.3 V against standard hydrogen electrode. This work revealed the feasibility of the AL-MEC system for the degradation of o-xylene and similar compounds, and provided insights into bioelectrochemical system design with high gaseous pollution removal capacity.

Enhancing performance evaluation and microbial community analysis of the biofilter for toluene removal by adding polyethylene glycol-600 into the nutrient solution

Polyethylene glycol-600 (PEG-600), as a carrier for slow release of organic substances, can improve the biocompatibility of packing fillers and the construction of biofilms. The gradient experiments were established to evaluate the feasibility of adding different content of PEG-600 to the biofilter for enhancing toluene removal. In particular, the evolution trend of microbial community embedded in packing fillers was measured by 16S rRNA-based gene sequencing. Results showed that the toluene removal efficiency of biofilter with 7.5% adding content of the PEG-600 was greatly improved, and the maximum elimination capacity of 152 g/(m³·h) was obtained. The introduction of PEG-600 enhanced the tolerance ability to withstand the transient impact loading and intensified the production of extracellular polymeric substances and bonding strength of biofilms. It should be noted that the abundance of Pseudomonas and Steroidobacter at genus level increased significantly. The microbial community evolved into a co-degradation system of toluene and PEG-600.