Inorganic Packing Materials Research Articles

Performance evaluation of a hybrid treatment system for the treatment of grey water

ABSTRACT The performance of a combined up-flow submerged aerated biological filter (SABF) and photocatalytic process (PC) for the treatment of grey water was studied. The removal of COD, hardness, alkalinity, and turbidity was considered. The removal efficiency of SABF using organic and inorganic packing materials was evaluated. The combined SABF and PC removed 100% of COD, up to an organic loading rate (OLR) of 0.21 ± 0.05 kg/m3/day at 12 h HRT, irrespective of the packing media. The fibrous outer shell of coconut fibres favoured turbidity removal, but both the organic and inorganic packing materials showed equal performance in the removal of physicochemical parameters of the grey water.

Biofiltration of methane in presence of ethylbenzene or xylene

Landfill gases (LFGs) are gaseous emissions containing several harmful compounds such as volatile organic compounds (VOCs), volatile inorganic compounds (VICs) along with methane (CH4) which is a powerful greenhouse gas. In the case of small or older landfills, disposal of LFG can be economically challenging, and a possible solution is biofiltration. Biofiltration of CH4 in the presence of two VOCs was studied, ethylbenzene (EB) for biofilter 1 (BF1) and xylene (X) for biofilter 2 (BF2). Both biofilters were packed with inorganic packing materials and operated with an empty bed residence time (EBRT) of 4.5 min. Methane concentrations varied from 2000 to 10,000 ppmv along with 2 concentrations for both VOCs i.e., 200 and 500 ppmv. In the case of individual VOC's removal, the acclimation period of the microorganisms to EB and X were close to 30 days, indicating a similar adaptation period for X and EB. The addition of CH4 under low inlet concentration of 2000 ppmv had minor effect on VOCs biodegradation such that the average VOC removal efficiencies (REs) remained above 85% for VOC inlet concentrations of 200 ppmv while the average CH4-RE were around 56% in both biofilters. When CH4 inlet concentration increased up to 10,000 ppmv, inhibition became an issue for all VOC concentrations and dropped VOC and CH4-REs down to 80% of their original values. The type and concentration of the VOC played a key role in the intensity of the inhibition. In general, mass transfer was controlling the elimination of the three substrates.

Biofilter with mixture of pine bark and expanded clay as packing material for methane treatment in lab-scale experiment and field-scale implementation.

Low methane (CH4) emission reduction efficiency (< 25%) has been prevalent due to inefficient biological exhaust gas treatment facilities in mechanic biological waste treatment plants (MBTs) in Germany. This study aimed to quantify the improved capacity of biofilters composed of a mixture of organic (pine bark) and inorganic (expanded clay) packing materials in reducing CH4 emissions in both a lab-scale experiment and field-scale implementation. CH4 removal performance was evaluated using lab-scale biofilter columns under varied inflow CH4 concentrations (70, 130, and 200gm-3) and corresponding loading rates of 8.2, 4.76, and 3.81gm-3h-1, respectively. The laboratory CH4 removal rates (1.2-2.2gm-3h-1) showed positive correlation with the inflow CH4 loading rates (4-8.2gm-3h-1), indicating high potential for field-scale implementation. Three field-scale biofilter systems with the proposed mixture packing materials were constructed in an MBT in Neumünster, northern Germany. A relatively stable CH4 removal efficiency of 38-50% was observed under varied inflow CH4 concentrations of 28-39gm-3 (loading rates of 1120-2340gm-3h-1) over a 24-h period. The CH4 removal rate was approximately 500-700gm-3h-1, which was significantly higher than relevant previously reported field-scale biofilter systems (16-50gm-3h-1). The present study provides a promising configuration of biofilter systems composed of a mixture of organic (pine bark) and inorganic (expanded clay) packing materials to achieve high CH4 emission reduction. Graphic abstract ᅟ.

Steady state and dynamic behaviors of a methane biofilter under periodic addition of ethanol vapors

Ethanol was added to a methane (CH4) biofilter with inorganic packing materials over three cycles based on increasing the gas flow rates from 3 to 6 and finally to 12 L min−1 corresponding to empty bed residence times (EBRT) of 6, 3 and 1.5 min. The steady state performance of the CH4 biofilter was studied for CH4 inlet loads (ILs) of 33, 66 and 132 gCH4 m−3 h−1 prior and after each ethanol cycle. In addition, the steady state removal of a mixture of CH4 and ethanol for a CH4/ethanol mass ratio of around 7.5 gCH4 g −1ethanol was evaluated over three cycles (EBRTs of 6, 3 and 1.5 min). In the absence of ethanol, the CH4 removal efficiency (RE) dropped from 35 to 7% due to an EBRT decrease from 6 to 1.5 min. In addition, the presence of ethanol resulted in a CH4 RE reduction at a constant EBRT in every cycle. The CH4 REs dropped from 35 to 29%, 17 to 13% and 7 to 0% for corresponding ethanol ILs of 4.5, 9 and 18 gethanol m−3 h−1 over the cycles. Moreover, the periodic presence of ethanol in the CH4 biofilter allowed the study of transient behaviors of the biofilter during ethanol addition and the biofilter recovery after each cycle. The CH4 RE reduction as a result of ethanol addition in each cycle was instantaneous. However, the CH4 RE recovery after completion of ethanol addition took 10, 14 and 25 days for ethanol ILs of 4.5, 9 and 18 gethanol m−3 h−1 respectively. The recovery time was related to the ethanol concentration in the leachate which were 1100 ± 200, 1100 ± 350 and 2500 ± 400 gethanol m−3leachate for corresponding ethanol ILs of 4.5, 9 and 18 gethanol m−3 h−1, respectively. Based on steady state and dynamic process conditions of the biofilter, the lowest gas flow rate of 3 L min−1 (EBRT of 6 min) produced the best performance when both pollutants were present (CH4 IL of 33 gCH4 m−3 h−1 and ethanol IL of 4.5 gethanol m−3 h−1).

Characterization and evaluation of poplar and pine wood in twin biotrickling filters treating a mixture of NH3, H2S, butyric acid, and ethylmercaptan

Biotrickling filters for waste gas treatment are often packed with expensive, inert packing materials. In this work, poplar and pine wood chips were evaluated as low‐cost packing materials in two biotrickling filters for the simultaneous treatment of a mixture of organic and inorganic volatile compounds. Bioreactors were operated at gas contact times of 22–34 s. Inlet loading rates of 3.5 ± 1.0 gN‐NH3 m−3h−1 and 6.5 ± 1.1 gS‐H2S m−3h−1 were supplied, while ethylmercaptan and butyric acid were fed at loads of 3.6 ± 1.2 and 6.0 ± 2.1 g m−3h−1, respectively. A thorough characterization of both packing materials revealed some differences in the physical–chemical properties, mainly in their water retentivity and buffer capacity. Despite of such differences, both bioreactors performed similarly. Bioreactors were able to achieve complete removal of NH3 and butyric acid, while H2S and EM removal efficiencies over 90% and 70%, respectively, were found. N‐species analyses in the leachate proved high nitrification rates in both biotrickling filters. Control of pH was essential for maintaining nitrification activity. Other oxidation processes were hardly affected by pH changes. Both woods showed potentially attractive as packing materials for biofiltration. Thus, availability and durability of woods are decisive factors to tip the balance. The work compares the performance of two biotrickling filters packed with two types of wood chips commonly used in biofilters. No previous works have directly compared the performance of two types of woods in biotrickling filters for the treatment of a range of organic and inorganic odorants because biotrickling filters are commonly packed with inert packing materials. Results indicated that the two types of woods tested behaved similarly and, more interestingly, showed equivalent treatment capacities than that of inert packing materials in the removal of a range of typical pollutants in odorant waste gases. Research is of particular interest for improving biofiltration knowledge. In addition, this research has large practical implications in the cost‐benefit of full‐scale biotrickling filtration systems because inorganic packing materials commonly used in biotrickling filters are much more expensive than organic packing materials. © 2016 American Institute of Chemical Engineers Environ Prog, 36: 171–179, 2017

Performance evaluation of a slow-release packing material-embedded functional microorganisms for biofiltration

ABSTRACTA composite packing material (CM-5) was prepared in this study, mainly consisting of compost with functional microorganisms, calcium carbonate (CaCO3), perlite, cement and plant fiber. To get stronger compressive strength, mass ratios of these components were optimized based on single factor experiments, and finally adding amounts of perlite, cement, plant fiber, CaCO3, compost and binder at 18%, 18%, 7%, 13%, 17% and 27%, respectively. According to the optimum proportion, CM-5 was extruded in cylindrical shape (12 mm in diameter and 20 mm in length) with a bulk density of 470 kg m−3, a moisture retention capacity of 49% and the microbial counts of × 105 CFU g−1 of packing material. The cumulative release rates of total organic carbon (TOC) and total nitrogen (TN) from CM-5 were 3.1% and 6.5%, respectively, after 19 times extraction in distilled water. To evaluate the H2S removal capacity, CM-5 was compared with an organic (corncob) and an inorganic (ceramsite) packing material in three biofilters. The results showed that CM-5 had higher H2S removal capacity compared with corncob and ceramsite. CM-5 could avoid the large fluctuation of pH value and pressure drop during the operation. The maximum H2S removal capacity of CM-5 was 12.9 g m−3 h−1 and the removal efficiency could maintain over 95.4% when the inlet H2S loading rate was lower than 11.3 g m−3 h−1 without any addition of nutrients and pH buffer substances. Besides, only 2–3 days were needed for the recovery of biofiltration performance after about two weeks of idle period.

Characterization and Selection of Packing Materials for Biofiltration of Rendering Odourous Emissions

Robust and cheap, biofiltration is one of the most used methods for the biological treatment of industrial gaseous odours and VOCs emissions. The chemical, physical and microbial properties, as well as the economical impact of 11 organic and inorganic packing materials potentially suitable for biofiltration, have been investigated in order to select the most relevant for the treatment of rendering gaseous emissions. Fibrous materials such as peat and coconut fibres are predisposed to compaction. Moreover, according to their low expected running period, their implementation remains expensive, such as activated carbon which induce overweening costs (>100,000€ an−1 for the treatment of 40,000 m3 h−1 with a 60-s empty bed gas residence time). Considering economical aspects, physico-chemical and biological properties, pines barks, composted wood mulch and expanded schist seem fit for this application. The performance of these materials was therefore investigated in a pilot-scale study conducted on a rendering site. According to its appropriate pH (8.62) and water-holding capacity (1.41 g g−1) and its highest nutrients content and colonization at the biofilter start-up (93 g of ATP m−3, 29.1013 CFU m−3), composted would mulch show the best odour removal efficiency during the 134 days of operation. Performances ranged between 75 and 93 % for the treatment of odourous inlet load between 1.16 and 10.10 · 106 ouE m−3 h−1 with an empty bed gas residence time of 47 s. However, the pressure drop of the compost bed decreased, suggesting structural changes which may impact the performances in the long term.

Startup and long-term performance of biotrickling filters packed with polyurethane foam and poplar wood chips treating a mixture of ethylmercaptan, H2S, and NH3

Treatment of a mixture of NH3, H2S, and ethylmercaptan (EM) was investigated for more than 15 months in two biotrickling filters packed with poplar wood chips and polyurethane foam. Inlet loads ranging from 5 to 10 g N-NH3 m−3 hr−1, from 5 to 16 g S-H2S m−3 hr−1, and from 0 to 5 g EM m−3 hr−1 were applied. During startup, the biotrickling filter packed with polyurethane foam was re-inoculated due to reduced biomass retention as well as a stronger effect of nitrogen compounds inhibition compared with the biotrickling filter packed with poplar wood. Accurate pH control between 7 and 7.5 favored pollutants abatement. In the long run, complete NH3 removal in the gas phase was achieved in both reactors, while H2S removal efficiencies exceeded 90%. EM abatement was significantly different in both reactors. A systematically lower elimination capacity was found in the polyurethane foam bioreactor. N fractions in the liquid phase proved that high nitrification rates were reached throughout steady-state operation in both bioreactors. CO2 production showed the extent of the organic packing material degradation, which allowed estimating its service lifetime in around 2 years. In the long run, the bioreactor packed with the organic packing material had a lower stability. However, an economic analysis indicated that poplar wood chips are a competitive alternative to inorganic packing materials in biotrickling filters. Implications: We provide new insights in the use of organic packing materials in biotrickling filters for the treatment of H2S, NH3, and mercaptans and compare them with polyurethane foam, a packing commonly used in biotrickling filters. We found interesting features related with the startup of the reactors and parameterized both the performance under steady-state conditions and the influence of the gas contact time. We provide relevant conclusions in the profitability of organic packing materials under a biotrickling filter configuration, which is infrequent but proven reliable from our research results. The report is useful to designers and users of this technology.

Treatment of a gaseous mixture by biofilters filled with an inorganic packing material: performance and influence of inoculation on removal efficiency levels

AbstractBACKGROUND: The impact of inoculation on performance and subsequent community structure is a critical question in gas biofiltration processes. Thus, the aim of this study is to evaluate the impact of inoculation on biofilters packed with an inorganic medium and fed with a gaseous mixture (oxygenated and sulphur compounds).RESULTS: Inoculated biofilters (BF1 and BF2 duplicates) exhibit higher overall removal performances and lower removal height (oxygenated: 100% at 50 cm and sulphur: 55% at 100 cm) than control biofilters (PC) (oxygenated: 94% and sulphur: 39% at 100 cm). The concentration of compounds was measured along the bed height using two sampling lines. For each biofilter, the evolution of removal efficiency as a function of height differs and depends on the line considered. At steady‐state, a divergence is observed between the bacterial communities of BFs that exhibited a similar stratification pattern of removal efficiency.CONCLUSION: Inoculation of biofilters seems to bring enough diversity to allow the emergence of fitted species resulting in higher pollutants removal and to strengthen the heterogeneity of biodegradation activities distribution along the column height. The divergence of the microbial community structure in BF samples can be explained by low selective pressure and high resource availability which influence the community composition. Copyright © 2012 Society of Chemical Industry

The Use of Inorganic Packing Materials during Methane Biofiltration

The objective behind this study is to select a suitable inorganic packing material for methane biofiltration. Three packing materials are to be compared: two rock materials (average particles' sizes: 2 and 5 mm) and one porous clay particles (average particle size of 7 mm). The main parameter used to assess the efficiency of the packing material is the methane elimination capacity. The study reveals that the rock material having an average particle size around 2 mm is to be preferred. This result is probably due to its high specific surface area and to its good surface properties as compared to the other 2 tested porous materials. The influence of the nonirrigation with the nutrient solution of the biofilter is also investigated. It has been found that nonirrigation of biofilter causes the biofilter performance to decrease significantly (e.g., 45% decrease in 1 week) even with the humidification of the gas phase prior to its introduction into the biofilter.

The influence of the gas flow rate during methane biofiltration on an inorganic packing material

AbstractThe influence of the gas flow rate (GFR), when varied between 1 and 5.5 L/min, on the conversion, the elimination capacity (EC) and the carbon dioxide production ${\rm (}P_{{\rm CO}_2 } )$, during the biofiltration of methane using a biofilter charged with an inorganic packing material, has been investigated. The methane concentrations considered for this purpose were selected from the operating range of 1300–12 000 ppmv. The experiments involved were conducted, using a nitrogen minimal salt nutrient solution, for the biofilter periodic irrigation, in which the nitrogen concentration was maintained at 0.75 g/L, and the phosphorus concentration was of 0.3 or 1.5 g/L.The results obtained from this study have confirmed the view that the GFR is a important parameter, the optimum values found, leading to methane conversions of ≥90%, being ≤2 L/min for inlet loads ≤55 g/m3/h. Based on this result, it was then established that the maximum volumetric load (VL) of methane in the biofilter must be estimated at around 0.075 m3 (methane)/m3 (biofilter)/h, that is, 6.8 m3 (polluted gas)/m3 (biofilter)/h. In addition, when the GFR is selected between 1 and 4.2 L/min, it has an influence on the EC. However, the GFR does not affect the $P_{{\rm CO}_2 }$ within the biofilter. It has also been established that the high phosphorus level (i.e., 1.5 g/L), present in the nutrient solution, is to be preferred in the biofilter.

Transient behavior of biofilter inoculated with Thiobacillus sp. IW to treat waste-air containing hydrogen sulfide

Hydrogen sulfide is heavier than air and is colorless, toxic and flammable, the gas odor threshold of which is about 0.47 ppbv, which causes nuisance odor at concentrations as low as about 8ppbv and corrosion problems in sewer systems. The transient behavior of biofilter packed with mixed media (of granular activated carbon and compost) inoculated with a pure culture of Thiobacillus sp. IW was observed at a height of four sampling ports to treat wasteair containing hydrogen sulfide in this investigation, which shall be used as control to be compared with the performance of a biofilter-involved integrated system for the treatment of waste-air containing hydrogen sulfide in a subsequent investigation. Unlike the previous studies of the other investigators, various process conditions were applied to successive biofilter runs in order to monitor and correlate each corresponding unsteady behavior of the biofilter at the height of each sampling port. During 10 days (20 times) after start-up of a biofilter hydrogen sulfide was continuously adsorbed on the media and that the adsorption of hydrogen sulfide was under way since the inlet loads of 1st and 2nd stage operations were very low. Afterwards it was obvious that the breakthrough curves at the 1st, 2nd, 3rd and 4th (exit) sampling ports responded rapidly to the change of operating conditions of a biofilter so that the breakthrough curve at each sampling port responded rapidly to approach a new state of saturation, which suggests that the adsorption capacity of biofilter-media may be relatively small or its affinity to hydrogen sulfide may be relatively high, compared to such volatile organic compound as ethanol. Up to the 3rd stage of operation the removal efficiency continued to be nearly 100%. However it began to decrease as inlet load increased. At the end of last stage of the biofilterrun removal efficiency was decreased and maintained at 94%. The maximum elimination capacity was observed to be ca. 95 g/m3/h, which was higher than that of the biofiltration-work of any other previous investigator except for that of the biofiltration-work with use of each of two inorganic packing materials (porous ceramics, calcinated and formed obsidian).

Comparison of the biological NH 3 removal characteristics among four inorganic packing materials

Four inorganic packing materials were evaluated in terms of their availability as a packing material of a packed tower deodorization apparatus (biofilter) from the viewpoints of biological NH 3 removal characteristics and some physical properties. Porous ceramics (A), calcinated cristobalite (B), calcinated and formed obsidian (C), granulated and calculated soil (D) were used. The superiority of these packing materials determined based on the values of nonbiological removal per unit weight or unit volume of packing material, complete removal capacity of NH 3 per unit weight of packing material per day or unit volume of packing material per day and pressure drop of the packed bed was in the order of A≅C>B≧D. Packing materials A and C with high porosity, maximum water content, and suitable mean pore diameter showed excellent removal capacity.

Comparison of the Biological NH3 Removal Characteristics among Four Inorganic Packing Materials.

Four inorganic packing materials were evaluated in terms of their availability as a packing material of a packed tower deodorization apparatus (biofilter) from the viewpoints of biological NH3 removal characteristics and some physical properties. Porous ceramics (A), calcinated cristobalite (B), calcinated and formed obsidian (C), granulated and calculated soil (D) were used. The superiority of these packing materials determined based on the values of non-biological removal per unit weight or unit volume of packing material, complete removal capacity of NH3 per unit weight of packing material per day or unit volume of packing material per day and pressure drop of the packed bed was in the order of A approximately = C > B > or = D. Packing materials A and C with high porosity, maximum water content, and suitable mean pore diameter showed excellent removal capacity.

Comparison of the Biological H2S Removal Characteristics among Four Inorganic Packing Materials.

Four inorganic packing materials were evaluated in terms of their availability as packing materials of a packed tower deodorization apparatus (biofilter) from the viewpoints of biological H2S removal characteristics and some physical properties. Among porous ceramics (A), calcinated cristobalite (B), calcinated and formed obsidian (C), granulated and calcinated soil (D), the superiority of these packing materials determined based on the values of non-biological removal per unit weight or unit volume of packing material, complete removal capacity of H2S per unit weight of packing material per day or unit volume of packing material per day and pressure drop of the packed bed was in the order of A approximately equal to C > D approximately equal to B, which is correlated with the maximum water content, porosity, and mean pore diameter.

Comparison of the biological H 2S removal characteristics among four inorganic packing materials

Four inorganic packing materials were evaluated in terms of their availability as packing materials of a packed tower deodorization apparatus (biofilter) from the viewpoints of biological H 2S removal characteristics and some physical properties. Among porous ceramics (A), calcinated cristobalite (B), calcinated and formed obsidian (C), granulated and calcinated soil (D), the superiority of these packing materials determined based on the values of nonbiological removal per unit weight or unit volume of packing material, complete removal capacity of H 2S per unit weight of packing material per day or unit volume of packing material per day and pressure drop of the packed bed was in the order of A⋍C > D⋍B, which is correlated with the maximum water content, porosity, and mean pore diameter.

Comparison of organic and inorganic packing materials in the removal of ammonia gas in biofilters

Two organic and two inorganic packing materials were compared with regard to the removal of ammonia gas in a biofilter inoculated with night-soil sludge. By gradually increasing the inlet load of ammonia, the complete removal capacity, which was defined as the inlet load of ammonia that was completely removed, and the maximum removal capacity of ammonia, which was the value when the removal capacity leveled off for each packing material, were estimated. Both values which were based on a unit volume of packing material, were higher for organic packing materials than inorganic ones. By using kinetic analysis, the maximum removal rate of ammonia, V m, and the saturation constant, K s, were determined for all packing materials and the values of V m for organic packing materials were found to be larger. By using the kinetic parameters, the removal rates for ammonia were compared among the four packing materials, and the organic packing materials showed superior performance for the removal of ammonia in the concentration range of 0–300 ppm as compared to inorganic packing materials.

Removal of a High Load of Ammonia Gas by a Marine Bacterium, Vibrio alginolyticus.

A newly isolated marine bacterium, Vibrio alginolyticus was used to remove a high load of ammonia gas. By a stepwise increase in ammonia supply over the concentration range of 120–2000 ppm (v/v), complete removal of ammonia was observed from the start of the experiment in a suspended culture of the bacterium in basal medium containing 3% NaCl. When cells were inoculated onto an inorganic packing material in a biofilter, and a high load of ammonia was introduced continuously under nonsterile conditions, the average percentage of gas removed exceeded 85% for a 61-d operation. The maximum removal capacity and the complete removal capacity were 22.8 g-N/kg-dry packing material/d and 18.6 g-N/kg-dry packing material/d, respectively, which were about four times larger than those obtained in nitrifying sludge inoculated onto the same packing material. During this operation, the nonsterile air supply had no adverse effect on the removability of ammonia by V. alginolyticus.

Removal of a high load of ammonia gas by a marine bacterium, Vibrio alginolyticus

A newly isolated marine bacterium, Vibrio alginolyticus was used to remove a high load of ammonia gas. By a stepwise increase in ammonia supply over the concentration range of 120–2000 ppm (v/v), complete removal of ammonia was observed from the start of the experiment in a suspended culture of the bacterium in basal medium containing 3% NaCl. When cells were inoculated onto an inorganic packing material in a biofilter, and a high load of ammonia was introduced continuously under nonsterile conditions, the average percentage of gas removed exceeded 85% for a 61-d operation. The maximum removal capacity and the complete removal capacity were 22.8 g-N/kg-dry packing material/d and 18.6 g-N/kg-dry packing material/d, respectively, which were about four times larger than those obtained in nitrifying sludge inoculated onto the same packing material. During this operation, the nonsterile air supply had no adverse effect on the removability of ammonia by V. alginolyticus.

Removal characteristics of high load ammonia gas by a biofilter seeded with a marine bacterium, Vibrio alginolyticus

When the cells of the newly isolated marine bacterium, Vibrio alginolyticus, were inoculated on to an inorganic packing material in biofilter, and a load of ammonia of 2.4–22.5 g-N kg−1dry packing material was introduced continuously under non-sterile conditions, the average amount of NH3removed exceeded 85% over 61-d operation. The maximum removal capacity and the complete removal capacity were 22.8 g-N kg−1dry packing material dand 18.6 g-N kg−1dry packing material d, respectively, which were about four times larger than those obtained in autotrophic nitrifying sludge inoculated on the same packing material.