Search Results (33)

Sulfide is a toxic and hazardous substance in the agricultural environment, which can cause damage to humans and livestock when exposed to large amounts of air. In this study, we performed one-factor optimization of the culture conditions and culture fractions of the Cellulosimicrobium sp. strain L1 and combined it with a biological trickling filter cell for the degradation of hydrogen sulfide for 24 consecutive days. The degradation effect of strain L1 and the biological trickling filter (BTF) on hydrogen sulfide was investigated, and the changes in intermediate products in the degradation process were briefly analyzed. The results showed that strain L1 had the highest conversion efficiency when incubated with 3 g/L sucrose as the carbon source and 1 g/L NH₄Cl as the nitrogen source at a temperature of 35 °C, an initial pH of 5, and a NaCl concentration of 1%. The concentration of thiosulfate increased and then decreased during the degradation process, and the concentration of sulfate increased continuously. When strain L1 was applied to the biological trickling filter, it could degrade 359.53 mg/m³ of H₂S. This study provides a deeper understanding of sulfide degradation in biological trickling filters and helps promote the development of desulfurization technology and the treatment of malodorous gasses produced by the accumulation of large quantities of livestock manure. Full article

This paper characterizes the composition of extracellular polymeric substances (EPSs) in different types of activated sludge (AS) processes and analyzes the biosorption of soluble organics when waste AS (WAS) is mixed with raw wastewater for primary carbon diversion. The fraction of AS organics identified as EPSs was 26% in a membrane bioreactor (MBR), 54% in conventional AS (CAS), and 51% in a trickling filter/solids contact (TF/SC) process. EPSs were found to be approximately 15% carbohydrates, 40% proteins, 40% humics, and 5% uronics in CAS and MBR AS. Biosorption was not correlated to the organic portion (VSS) of the WAS; however, statistically significant correlations were found for the total amount of EPSs (for TF/SC and CAS) and the protein fraction (for TF/SC and MBR) in the VSS. EPSs from different types of AS biosorbed the same amount of soluble organics, removing 1.43 ± 0.15 (n = 16) mg of soluble chemical oxygen demand (sCOD), and 1.20 ± 0.18 (n = 16) mg of truly soluble COD (ffCOD), per mg of cation exchange resin (CER) total extracted EPSs. Utilizing multiple extraction methods in series (CER–base–sulfide) increased EPS extraction yields by nearly 100% relative to CER alone and indicated different EPS fractionization for CAS (a smaller fraction of carbohydrates and a larger fraction of humics). Full article

Environmental pollution is an issue of particular concern, specifically when industrial waste products are not subjected to appropriate treatment. Among various industries in the agri-food sector, the brewing industry holds a significant position in this context, given that beer stands as the predominant choice of consumers. Brewery waste generates significant quantities of organic substances, along with ammonium nitrogen and phosphorus. Among the various methods for their treatment, adsorption has received substantial attention due to its cost-effectiveness and operational simplicity. The present study investigates the adsorption capacity of two materials, zeolite and palygorskite, for the removal of ammonium nitrogen and brewery waste, using columns and batches. Simultaneously, desorption and regeneration experiments were conducted, and the effect of pH on their effectiveness was also examined. To understand the adsorption mechanisms, isotherm and kinetic models have been estimated. The results of the experiments have demonstrated a marked adsorption efficiency of the adsorbent materials, surpassing 90%. In comparison, zeolite has exhibited a better adsorption capacity in the removal of ammonium nitrogen, while palygorskite has shown greater aptitude for phosphorus removal. The purpose of these experiments was to investigate the adsorption capacity of these two materials as a potential medium for brewery wastewater treatment (e.g., as part of adsorption filter, trickling filters, and constructed wetlands). Full article

Currently, only 50% of concrete produced from construction and demolition waste is being recycled in Europe. This falls short of the European Union’s target of 70% by 2020. Moreover, this figure only considers coarse fractions (>4 mm), as technical issues arise when using fine fractions. In pursuit of a complete circular life for recycled concrete, this investigation explores the potential use of fine fractions to enhance the physicochemical conditions and reduce the element concentration of acid mine drainage. Two trickling sets were prepared using a filter holder, with acidic waters passing through a layer of recycled concrete aggregates. Results revealed an immediate increase in water pH to neutral levels, a reduction in solution oxidation, and the complete, or near-complete retention, of potentially toxic elements by the substrate (with retention percentages of over 99.9% for Al and Fe, between 43.1% and 61.1% for S, over 91.1% for Zn, and over 99.1% for Cu). The experiment also showed a significant increase in Ca levels (tripling the initial value) and some Mg in the water, which could promote the subsequent precipitation of carbonates and the retention of trace metals. In summary, this study demonstrates the effectiveness of using recycled concrete aggregates in a laboratory setting. Further investigation is necessary to evaluate the feasibility of implementing this technique at the pilot scale. Full article

In recent years, styrene waste gas has become a hot issue in the waste gas treatment industry due to its hydrophobicity and easy polymerization. This study is aimed at the problems of long empty bed residence time and low removal capacity of waste gas from styrene degradation by bio-trickling filter (BTF). A novel bio-trickling filter (NBTF) that we designed was used to explore the effects of styrene inlet concentration, empty bed residence time (EBRT), and starvation period on the performance of NBTF in the degradation of styrene waste gas. The experimental results show that the NBTF can be started in 17 days; when the inlet concentration was lower than 1750 mg/m³ and the EBRT was 59.66 s, the removal efficiency (RE) of styrene can reach 100%. When the inlet concentration was 1000 mg/m³ and the EBRT was greater than 39.77 s, styrene waste gas can also be completely degraded. The above proves that NBTF can complete the degradation of styrene waste gas with high concentration under the condition of short EBRT; in the whole operation process, the maximum elimination capability (EC) of styrene was 112.96 g/m³/h, and NBTF shows excellent degradation performance of styrene. When the starvation period was 2 days, 7 days and 15 days, respectively, NBTF can recover high degradation performance within 2 days after restart. The NBTF has good operation performance in 124 days of operation, which proves that the NBTF can effectively degrade styrene waste gas. This provides a reference basis for industrial treatment of styrene waste gas in the future. Full article

A pilot-scale biotrickling filter (BTF) was operated in counter-current flow mode under anoxic conditions, using diluted agricultural digestate as inoculum and as the recirculation medium for the nutrient source. The process was tested on-site at an agricultural fermentation plant, where real biogas was used. The pilot plant was therefore exposed to real process-related fluctuations. The purpose of this research was to attest the validity of the filtration process for use at an industrial-scale by operating the pilot plant under realistic conditions. Neither the use of agricultural digestate as trickling liquid and nor a BTF of this scale have previously been reported in the literature. The pilot plant was operated for 149 days. The highest inlet load was 8.5 gS-H₂Sm⁻³h⁻¹ with a corresponding removal efficiency of 99.2%. The pH remained between 7.5 and 4.6 without any regulation throughout the complete experimental phase. The analysis of the microbial community showed that both anaerobic and anoxic bacteria can adapt to the fluctuating operating conditions and coexist simultaneously, thus contributing to the robustness of the process. The operation of an anoxic BTF with agricultural digestate as the trickling liquid proved to be viable for industrial-scale use. Full article

It is expected that, by 2050, the rapid rise in population and simultaneous urbanization shall deplete clean water supplies. Domestic wastewater (DWW) contains inorganic and organic components that can be harmful to aquatic organisms. Traditional remediation approaches (physical, chemical and biological) can be used on-site or off-site to purify polluted domestic water (activated sludge, built-wetlands, stabilization ponds, trickling filters and membrane bioreactors), and each has its own advantages and limitations. Biosorption through microorganisms, bacteria (microbe-mediated remediation), fungi (mycoremediation) and algae (phycoremediation) has shown promising results in removing toxic chemicals and nutrients. The type of waste and its concentration, heterogeneity level and percentage of clean-up required; and the feasibility of the clean-up technique and its efficiency, practicability, operational difficulties, environmental impact and treatment costs are all factors that are to be considered when choosing a technique for domestic wastewater treatment (DWWT). This review focuses on the roles of conventional methods in DWWT, including their merits, demerits and future prospects. It promotes the concept of “reduce, reuse and recycle” of DWWT and also highlights the problem of emerging contaminants in WWT regimes. We provide insights into the different membrane filtration procedures and water purification techniques and the synergism of conventional and non-conventional WWT strategies for human and environment health security. Full article

Biological methanation is the production of CH₄ from CO₂ and H₂. While this approach to carbon capture utilization have been widely researched in the recent years, there is a gap in the technology. The gap is towards the flexibility in biomethanation, utilizing biological trickling filters (BTF). With the current intermittent energy system, electricity is not a given surplus energy which will interfere with a continuous operation of biomethanation and will result in periods of operational downtime. This study investigated the effect of temperature and H₂ supply during downtimes, to optimize the time needed to regain initial performance. Short (6 h), medium (24 h) and long (72 h) downtimes were investigated with combinations of three different temperatures and three different flow rates. The results from these 27 experiments showed that with the optimized parameters, it would take 60 min to reach 98.4% CH₄ in the product gas for a short downtime, whereas longer downtimes needed 180 min to reach 91.0% CH₄. With these results, the flexibility of biomethanation in BTFs have been proven feasible. This study shows that biomethanation in BTFs can be integrated into any intermittent energy system and thereby is a feasible Power-2-X technology. Full article

Large-flow waste gas generated from the pharmaceutical and chemical industry usually contains low concentrations of VOCs (volatile organic compounds), and it is also the key factor that presents challenges in terms of disposal. To date, due to the limitations of mass transfer rate and microbial degradation ability, the degradation performance of VOCs using the biological method has not been ideal. Therefore, in this study, the sludge from a chlorobenzene-containing wastewater treatment plant was inoculated into our experimental bio-trickling filter (BTF) to explore the feasibility of domestication and degradation of gaseous chlorobenzene by highly active microorganisms. The kinetics of its mass transfer reaction and microbial community dynamics were also discussed. Moreover, the main process parameters of BTF for chlorobenzene degradation were optimized. The results showed that the degradation effect of chlorobenzene reached more than 85% at an inlet concentration of chlorobenzene 700 mg·m⁻³, oxygen concentration of 10%, and an empty bed retention time (EBRT) of 80 s. The mass transfer kinetic analysis indicated that the process of chlorobenzene degradation in the BTF occurred between the zero-stage reaction and the first-stage reaction. This BTF contributed significantly to the biodegradability of chlorobenzene, overcoming the limitation of gas-to-liquid/solid mass transfer of chlorobenzene. The analysis of the species diversity showed that Thermomonas, Petrimona, Comana, and Ottowia were typical organic-matter-degrading bacteria that degraded chlorobenzene efficiently with xylene present. Full article

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. Full article

This research estimates the efficiency of domestic wastewater treatment in the removal of organic pollutants and nitrogen compounds with a two-stage treatment sequence (an activated sludge reactor in the first stage, and a trickling filter in the second stage), and with the application of floating carriers in the activated sludge reactor. The materials “Polyvom”, “Polystyrene” and “Bioballs” were adopted as floating carriers with previously determined filling ratios in the reactor volume of 10%, 20% and 20%, respectively. After the first stage of the study, it was found that the most effective treatment was achieved using the “Polyvom” material. Therefore, only this floating carrier was considered in the second and third stages of the study. Within the stages of the research, lab-scale benches operated under different operation modes of the treatment sequence. At the end of the study, it was possible to achieve the following levels of purification: BOD₅ (2.1 mg/L), NH₄ (0.4 mg/L), NO₂ (1.0 mg/L), and NO₃ (25 mg/L). The mean values of the concentrations of BOD, NH₄, and NO₃ met the requirements, but the concentration of NO₂ exceeded the requirements (1.0 mg/L vs. 0.08 mg/L). These results were achieved under a hydraulic retention time in the activated sludge reactor of 8 h, and the MLSS for the free-floating and immobilized activated sludge was 0.2 and 0.9 g/L, respectively. Full article

The National Egyptian Agenda 2030 recently adopted the concepts of sustainable cities, mitigating and adapting to climate change. This study responded to these concepts by treating sewage to reuse it in softscaping and recycling sludge to reduce energy consumption and support heating systems by producing biogas. Of the limitations of this study, it focuses on a compound to propose a model to increase the sustainability of Egyptian cities. This study used many technologies, such as biological treatment processes, activated sludge, trickling filters, and fixed bioreactors. However, Membrane bioreactors (MBRs) have seemed to be the most suitable technology because of their low cost and footprint. Additionally, a pilot laboratory was established to simulate the sewage treatment plant. It consisted of a primary sedimentation tank followed by an MBR tank and a chlorine disinfection tank, where the sludge was fed into a cylindrical anaerobic digester. The amount of sludge collected generated 41.5 mL/day of biogas. The application of this large-scale batch reactor will produce around 38 m3/day of biogas. Applying the findings of this study to the treatment and reuse of domestic sewage and sludge can provide up to 50% of the water needed for the green area of the compound. Full article

Extracellular polymeric substances (EPS) reportedly make up approximately half of the organic matter in activated sludge (AS), and therefore strongly influence AS properties. This study evaluated the component fractions of EPS normalized to volatile suspended solids (VSS) in waste activated sludge (WAS) from a trickling-filter-solids contact process (TF/SC) and its ability to biosorb organic matter from raw wastewater with 30 min of contact time. Biosorption is the process in which organic matter (carbohydrates, proteins, humic acids, DNA, uronic acids, and lipids) in a sorbate, such as raw wastewater, sorbs onto a sorbent such as WAS. A statistically significant correlation was found between both the total concentration of EPS and the proteins component of the EPS and the biosorption removal of soluble chemical oxygen demand (sCOD) and truly soluble COD (ffCOD). Thus, the biosorption of soluble forms of COD can accurately be predicted by quantifying just the amount of proteins in WAS-associated EPS. No significant correlations were found for the biosorption of colloidal COD (cCOD). WAS biosorbed 45–75 mg L⁻¹ of COD in 30 min. WAS absorbed or stored the proteins fraction of the soluble microbial products (SMP) during the biosorption process. Higher concentrations of humic acids were found in the biosorption process effluent than in the untreated wastewater, which warrants further study. Longer cation exchange resin (CER) extraction times yielded more total EPS from the sludge: 90 ± 9, 158 ± 3, and 316 ± 44 mg g⁻¹ VSS, for 45-min, 4-h, and 24-h extraction times, respectively. Thus, EPS extracted represented only 9%, 15.8%, and 31.6% of the VSS, respectively, raising questions about whether the accurate characterization of EPS can be performed using the typical extraction time of 45 min due to different extraction rates for different components. It was found that the humic acids fraction was extracted much more slowly than the other fractions. Full article

The aim of the present study is to assess the wastewater treatment efficiency of a low-cost pilot-scale trickling filter (TF) system under a prevailing temperature range of 12 °C–38 °C. Operational data (both influent and effluent) for 330 days were collected from the pilot-scale TF for various physicochemical and biological parameters. Average percentage reductions were observed in the ranges of 52–72, 51–73, 61–81, and 74–89% for BOD₅, COD, TDS, and TSS, respectively, for the whole year except the winter season, where a 74–88% reduction was observed only for TSS, whilst BOD₅, COD, and TDS demonstrated reductions in the ranges of 13–50, 13–49, and 23–61%, respectively. Furthermore, reductions of about 43–55% and 57–86% in fecal coliform count were observed after the 1st and 6th day of treatment, respectively, throughout study period. Moreover, the pilot-scale TF model was based on zero-order kinetics calibrated at 20 °C using experimental BOD₅ data obtained in the month of October to calculate the k₂₀ value, which was further validated to determine the k_t value for each BOD₅ experimental setup. The model resulted in more accurate measurements of the pilot-scale TF and could help to improve its ability to handle different types of wastewater in the future. Full article

The article presents the results of an experimental study on the clarification of biologically treated wastewater in a clarifier with a suspended sludge layer. The pilot plant was receiving effluent from trickling filters treating municipal wastewater. An experimental clarifier worked under steady-state conditions considering the influent characteristics and variable operating parameters in terms of flow velocities and height of the suspended layer. From the experimental dependences between different technological parameters it was found that the optimum range of the upward flow velocities providing a dynamic equilibrium of the suspended layer was 0.6–1.4 mm/s. Upward flow velocities below 0.5 mm/s can lead to sludge compaction at the bottom of the unit, while values greater than 1.8 mm/s may cause sludge washout. It was also found that higher suspended layer height values favor higher efficiency of the clarifier and can achieve suspended solids in the discharge of less than 5.0 mg/L; this height should be greater than 0.6 m Technological efficiency of the experimental clarifier was significantly higher than the conventional unit and was comparable with tertiary treatment technologies. Full article