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Background Primary Sjögren's syndrome (pSS) is an autoimmune disease that leads to the destruction of exocrine glands and multisystem lesions. Abnormal proliferation, apoptosis, and differentiation of CD4+ T cells are key factors in the pathogenesis of pSS. Autophagy is one of the important mechanisms to maintain immune homeostasis and function of CD4+ T cells. Human umbilical cord mesenchymal stem cell-derived exosomes (UCMSC-Exos) may simulate the immunoregulation of MSCs while avoiding the risks of MSCs treatment. However, whether UCMSC-Exos can regulate the functions of CD4+ T cells in pSS, and whether the effects via the autophagy pathway remains unclear. Methods The study analyzed retrospectively the peripheral blood lymphocyte subsets in pSS patients, and explored the relationship between lymphocyte subsets and disease activity. Next, peripheral blood CD4+ T cells were sorted using immunomagnetic beads. The proliferation, apoptosis, differentiation, and inflammatory factors of CD4+ T cells were determined using flow cytometry. Autophagosomes of CD4+ T cells were detected using transmission electron microscopy, autophagy-related proteins and genes were detected using western blotting or RT-qPCR. Results The study demonstrated that the peripheral blood CD4+ T cells decreased in pSS patients, and negatively correlated with disease activity. UCMSC-Exos inhibited excessive proliferation and apoptosis of CD4+ T cells in pSS patients, blocked them in the G0/G1 phase, inhibited them from entering the S phase, reduced the Th17 cell ratio, elevated the Treg ratio, inhibited IFN-γ, TNF-α, IL-6, IL-17A, and IL-17F secretion, and promoted IL-10 and TGF-β secretion. UCMSC-Exos reduced the elevated autophagy levels in the peripheral blood CD4+ T cells of patients with pSS. Furthermore, UCMSC-Exos regulated CD4+ T cell proliferation and early apoptosis, inhibited Th17 cell differentiation, promoted Treg cell differentiation, and restored the Th17/Treg balance in pSS patients through the autophagy pathway. Conclusions The study indicated that UCMSC-Exos exerts an immunomodulatory effect on the CD4+ T cells, and maybe as a new treatment for pSS.

Interleukin-21 (IL-21), a crucial immune regulatory molecule, belongs to the common γ-chain family of type I cytokines, and exerts pleiotropic effects on multiple immune cell types in mammals. However, the characteristics and functions of fish IL-21 remain unclear. To further investigate the molecular mechanism of IL-21 in teleosts, we first cloned and identified the IL-21 gene (designated shIL-21) of the snakehead (Channa argus). The full-length open reading frame of shIL-21 is 438 bp in length, and encodes a predicted protein of 145 amino acid residues. A sequence analysis showed that shIL-21 has the typical structural characteristics of other IL-21 proteins, containing four α-helices and four conserved cysteine residues. In a phylogenetic analysis, shIL-21 clustered within a subgroup of IL-21 proteins from other teleost species and shared its closest evolutionary relationship with that of Lates calcarifer. The expression analysis showed that shIL-21 was ubiquitously expressed in all the healthy snakehead tissues tested, albeit at different levels. After infection with Nocardia seriolae or Aeromonas schubertii, the relative expression of shIL-21 was mainly upregulated in the head kidney and spleen in vivo. Similarly, after stimulation with the three pathogen analogues lipoteichoic acid, lipopolysaccharides, and polyinosinic-polycytidylic acid, the expression of shIL-21 was also induced in head kidney leukocytes in vitro. A recombinant shIL-21 protein was expressed and purified, and promoted the proliferation of head kidney leukocytes, induced the expression of genes encoding critical signaling molecules in the Janus kinase (JAK) and signal transducer and activator of transcription (STAT) pathway, including JAK1, JAK3, STAT1, and STAT3, and induced the expression of endogenous shIL-21 and genes encoding several key proinflammatory cytokines (tumor necrosis factor-α, interferon-γ, and IL-1β). Taken together, these preliminary findings suggest that shIL-21 is involved in the immune defense against bacterial infection, in leukocyte proliferation, and in the activation of the JAK-STAT pathway. They thus extend the functional studies of IL-21 in teleosts.

Background: Primary Sjögren's syndrome (pSS) is an autoimmune disease that leads to the destruction of exocrine glands and formation of multisystem lesions. Abnormal proliferation, apoptosis, and differentiation of CD4+ T cells are key factors in the pathogenesis of pSS, seriously affecting the appearance, progression, and outcome of the disease. Human umbilical cord mesenchymal stem cell-derived exosomes (UCMSC-Exos) may effectively simulate the immunoregulatory and tissue repair functions of MSCs while avoiding the risks associated with MSCs treatment. Hence, UCMSC-Exos treatment is expected to become a new treatment for pSS. However, if UCMSC-Exos can regulate the abnormal proliferation, apoptosis, and differentiation of CD4+ T cells in pSS and the specific underlying mechanisms remain to be elucidated. Methods: UCMSC-Exos were isolated and identified. Peripheral blood CD4+ T-cells were sorted using immunomagnetic beads. The proliferation, apoptosis, differentiation, and inflammatory factors of CD4+ T cells were determined using flow cytometry. Autophagosomes of CD4+ T cells were detected using transmission electron microscopy, autophagy-related proteins were detected using western blotting, and autophagy-related genes were detected using RT-PCR. Results: UCMSC-Exos inhibited excessive proliferation of peripheral blood CD4+ T cells in pSS patients, blocked the G0/G1 phase transition, inhibited S phase cells, suppressed excessive apoptosis of CD4+ T cells, reduced the Th17 cell ratio, elevated the regulatory T cell (Treg) ratio, restored the Th1/Th2 and Th17/Treg balance, inhibited the CD4+ T cell-associated pro-inflammatory factors IFN-γ, TNF-α, IL-6, IL-17A, and IL-17F secretion, and promoted anti-inflammatory factor IL-10 and TGF-β secretion. UCMSC-Exos reduced the elevated autophagy levels in the peripheral blood CD4+ T cells of patients with pSS. Furthermore, UCMSC-Exos regulated CD4+ T cell proliferation and early apoptosis in pSS patients through the autophagy pathway, inhibited Th17 cell differentiation, promoted Treg cell differentiation, and restored the Th17/Treg balance. Conclusions: UCMSC-Exos regulate CD4+ T cell proliferation, apoptosis, and differentiation in patients with pSS through the autophagy pathway and exhibit immunoregulatory effects. These results provide an important theoretical and experimental foundation for exploring UCMSC-Exos as a new treatment for pSS and its application in clinical transformation.

Ethanol sensors with ultrafast response and high sensitivity have attracted much attention to be applied to daily industrial production processes. In this work, graphene oxide-aniline (GOA) sensors are proposed to meet the requirements of detecting ethanol concentration. Graphene oxide is an outstanding material that has excellent electrical and thermal conductivity, large specific surface area, and high carrier mobility. Because of its special bonding reactions, GOA has advantages of good dispersibility, good electrical conductivity, insolubility in water, and strong plasticity. When testing ethanol concentration with sensors, there will be a lag time, which determines the sensitivity of the sensors. To the best of our knowledge, the GOA sensors in this work have the fastest response time, which is only 27 ms. The GOA ethanol sensors show a good ethanol sensing performance, including excellent sensitivity, cycle stability, and long-term stability.

Objective To investigate the clinical features of anti-signal recognition particle (SRP) antibody-positive patients with dermatomyositis/clinically amyopathic dermatomyositis (DM/CADM) . Methods Clinical data were collected from 90 patients with DM/CADM, who were hospitalized at the Department of Dermatology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine from June 2015 to July 2017. Immunoblotting assay was performed to determine the serum level of anti-SRP antibody in these patients. Statistical analysis was carried out using t test and Chi-square test. Results Of the 90 patients with DM/CADM, 11 (12.2%) were positive for serum anti-SRP antibody, including 6 with DM and 5 with CADM. Among 82 adult patients with DM/CADM, the prevalence of malignant tumors was significantly higher in the patients with anti-SRP antibody than in those without (7/9 vs. 31.5%[23/73], χ2 = 7.394, P = 0.006) . The 11 patients with anti-SRP antibody had typical DM skin lesions, and their cutaneous dermatomyositis disease area and severity index (CDASI) was 18.1 ± 2.9. The prevalence of "angel wings sign" (aliform erythema on the trunk) was significantly higher in the patients with anti-SRP antibody than in those without (7/11 vs. 29.9%[20/67], Fisher′s exact test, P = 0.028) . The positive rate of antinuclear antibody was significantly higher in the patients with anti-SRP antibody than in those without (4/8 vs. 16.7%[13/78], χ2 = 6.053, P = 0.014) . Magnetic resonance imaging of muscles of both thighs of the 10 patients with anti-SRP antibody (6 with DM and 4 with CADM) showed the presence of abnormal signals in the thigh muscle group in 8, swelling of the muscle group in 2, subcutaneous edema in 2, myofascial swelling in 1, and no abnormities in 2. No interstitial lung disease or myocardial involvement was observed in the patients with anti-SRP antibody. Conclusions The anti-SRP antibody-positive patients with DM/CADM showed a high prevalence of "angel wings sign" , and a high risk of malignant tumors. Early detection of the anti-SRP antibody in patients with DM/CADM is helpful to predict the occurrence of malignant tumors. Key words: Dermatomyositis; Polymyositis; Signal recognition particle; Skin manifestations

Objective We aimed to determine the capacity of drug-eluting stent (DES) over-expansion in left main coronary artery disease. Methods Left main interventions with the largest available DES platforms (4.0 mm) and post-dilation performed with large non-compliant balloons (≥ 4.5 mm) were included. Maximal stent diameter (mm) and area (mm2) were measured using post-intervention intravascular ultrasound (IVUS). Stent diameter and area were calculated with the balloon diameter and inflation pressure. The diameter and area expansion indices were defined as follows: maximal/calculated stent diameter and maximal/calculated stent area, respectively. Results Twenty-three consecutive patients were included. The maximal stent diameter was 4.40 mm (4.30–4.80 mm), and 22 of 23 patients showed a diameter expansion index greater than 0.90. The area expansion index was 0.862. The expansion index Conclusions DESs with a nominal diameter of 4.0 mm can be effectively over-expanded in left main coronary artery disease. Achievement of predicted stent area can be affected by calcification.

Table S1. Correlation Models of CTFCindex and Topological Parameters. (DOC 64Â kb)

The effects of gas empty bed contact time (EBCT), biofilter configuration, and types of volatile organic compounds (VOCs) were evaluated to assess the performance of rotating drum biofilters (RDBs), especially at low EBCT values. Three types of pilot-scale RDBs, a single-layer RDB, a multi-layer RDB, and a hybrid RDB, were examined at various gas EBCTs but at a constant VOC loading rate. Diethyl ether, toluene, and hexane were used separately as model VOC. When EBCT increased from 5.0 to 60s at a constant VOC loading rate of 2.0kgCOD/(m(3)day), ether removal efficiency increased from 73.1% to 97.6%, from 81.6% to 99.9%, and from 84.0% to 99.9% for the single-layer RDB, the multi-layer RDB, and the hybrid RDB, respectively, and toluene removal efficiency increased from 76.4% to 99.9% and from 84.8% to 99.9% for the multi-layer RDB and the hybrid RDB, respectively. When hexane was used as the model VOC at a constant loading rate of 0.25kgCOD/(m(3)day), hexane removal efficiency increased from 31.1% to 57.0% and from 29.5% to 50.0% for the multi-layer RDB and hybrid RDB, respectively. The single-layer, multi-layer, and hybrid RDBs exhibited, respectively, the lowest, middle, and highest removal efficiencies, when operated under similar operational loading conditions. Hexane exhibited the lowest removal efficiency, while diethyl ether displayed the highest removal efficiency. The data collected at the various EBCT values correlated reasonably well with a saturation model. The sensitivity of removal efficiency to EBCT varied significantly with EBCT values, VOC properties, and biofilter configurations. Process selection and design for RDB processes should consider these factors.

Uneven distribution of volatile organic compounds (VOCs) and biomass, and excess biomass accumulation in some biofilters hinder the application of biofiltration technology. An innovative multilayer rotating drum biofilter (RDB) was developed to correct these problems. The RDB was operated at an empty bed contact time (EBCT) of 30 s and a rotational rate of 1.0 r/min. Diethyl ether was chosen as the model VOC. Performance of the RDB was evaluated at organic loading rates of 32.1, 64.2, 128, and 256 g ether/(m3 x h) (16.06 g ether/(m3 x h) approximately 1.0 kg chemical oxygen demand (COD)/(m3 x d)). The EBCT and organic loading rates were recorded on the basis of the medium volume. Results show that the ether removal efficiency decreased with an increased VOC loading rate. Ether removal efficiencies exceeding 99% were achieved without biomass control even at a high VOC loading rate of 128 g ether/(m3 x h). However, when the VOC loading rate was increased to 256 g ether/(m3 x h), the average removal efficiency dropped to 43%. Nutrient limitation possibly contributed to the drop in ether removal efficiency. High biomass accumulation rate was also observed in the medium at the two higher ether loading rates, and removal of the excess biomass in the media was necessary to maintain stable performance. This work showed that the RDB is effective in the removal of diethyl ether from waste gas streams even at high organic loading rates. The results might help establish criteria for designing and operating RDBs.

A hybrid bioreactor, combining an activated sludge process (ASP) and a rotating drum biofilter (RDB), was developed and evaluated for the treatment of volatile organic compounds (VOCs) in waste gas streams. The effects of the influent VOC concentration and the organic loading rate on the VOC removal efficiency and on the pattern of biomass accumulation were investigated. Toluene was used as the model VOC, the flow rate of the waste gas stream was 0.59 L/s, and the empty-bed retention time (EBRT) in the ASP portion was 46 s with an actual retention time of about 2 s. The EBRT in the RDB portion was 38 s based on the drum volume. When the VOC feed concentration increased from 221 to 884 mg toluene/m3 (from 57.2 to 229 ppm), correspondingly the organic loading rate of the hybrid bioreactor increased from 1.58 to 6.32 kg chemical oxygen demand/m3/day (from 0.505 to 2.02kg toluene/m3/day) based on the drum volume, both the ASP and RDB decreased, and the overall toluene removal efficiency declined from 99.8 to ...

A rotating drum biofilter (RDB) with multi-layered foam media was developed for the improvement of current biofiltration technology. The biofilter was used to investigate the effects of organic loadings and influent volatile organic compound (VOC) concentrations on VOC removal efficiency and biomass accumulation. These effects were evaluated using diethyl ether and toluene separately as model VOCs at an empty bed contact time (EBCT) of 30 s. When the toluene loading increased from 2.0 to 4.0 and 8.0 kgCOD m-3 day-1, toluene removal efficiency of the biofilter decreased from over 99% to 78% and 74%, respectively. The biomass distribution was found to be more even within the medium when removing toluene than when removing diethyl ether. Higher organic loading also resulted in the more even distribution of the biomass. The ratios of biomass accumulation rates in the medium of the outermost, middle and innermost layers ranged from 1:0.11:0.02 when removing diethyl ether at 2.0 kgCOD m-3 day-1 to1:0.69:0.51 when removing toluene at 8.0 kgCOD m-3 day-1. Review of these ratios revealed three biomass accumulation patterns: surface pattern, in-depth pattern and shallow pattern. Different patterns represent different removal mechanisms in the biofiltration process. Improved biofilter design and operation should be based on the biomass accumulation pattern.

Two types of rotating drum biofilters were tested to investigate the effect of medium configuration on biofilter performance for removing volatile organic compounds (VOCs) from waste gas streams. One was a single-layer biofilter that consisted of a thick layer of open-pore reticulated polyurethane foam media. The other was a multi-layer biofilter that used a set of four concentric thinner layers of the media. The effect of the two different media configurations was examined using diethyl ether as a model VOC at various organic loading rates. The results showed that the multi-layer biofilter could maintain more stable and higher ether removal efficiencies at gas empty bed contact time (EBCT) of 30 s than the single-layer biofilter at gas EBCT of 90 s, and at organic loading rates ranging from 2.0 to 8.0 kg COD m−3 day−1 (32.1 to 128.4 g ether m−3 h−1), all based on the medium volume. The multi-layer biofilter also exhibited a more even biomass distribution on the concentric surface at a medium depth than the single-layer biofilter, which suggests a reduced possibility of short-circuiting of gas streams and, consequently, better performance.

This paper is a summary of the various factors influencing weathering of oil after it has been released into the environment from a spill incident. Special emphasis has been placed on biodegradation processes. Results from two field studies conducted in 1994 and 1999 involving bioremediation of an experimental oil spill on a marine sandy shoreline in Delaware and a freshwater wetland on the St. Lawrence River in Quebec, Canada have been presented in the paper.

In-stent restenosis (ISR) is one of the major factors affecting long-term outcomes of percutaneous coronary interventions. Vascular endothelial growth factor (VEGF) has been hypothesized to have a positive role in preventing ISR, however, this remains controversial. The aim of the present study was to assess whether nanoparticles can be used to deliver VEGF to injured arteries and whether this is beneficial in preventing restenosis. New Zealand White rabbits were randomly divided into a control group, an empty nanoparticles group and a VEGF nanoparticles group (n=6 in each group). Polylactic-polyglycolic acid VEGF nanoparticles were prepared using a phacoemulsification method. A rabbit model of restenosis was established following abdominal aorta balloon injury, and VEGF gene nanoparticles, empty nanoparticles or normal saline were delivered locally at the site of injury via a GENIE Catheter™ perfusion balloon. Intimal proliferation determination and immunohistochemistry analysis were performed at day 28 following arterial injury. Compared with the control and empty nanoparticle groups, the neointima area (0.49±0.09, 0.48±0.08 and 0.19±0.11 mm2, respectively; P

The affect of nitrate concentration and reactor backwashing on biofilter performance is evaluated using a dynamic mathematical model of the biodegradation process of volatile organic compounds in a trickle bed biofilter packed with uniform synthetic solids. Experimental observations from a bench-scale biofilter system treating ether were used to develop and validate the model. Experience acquired in biofiltration of volatile organic compounds has demonstrated that although these two factors—nitrate and backwashing—are secondary when organic packing material is used, they are essential when the packing media is synthetic. The operation of a synthetic media packed reactor requires the addition of nutrients necessary for biodegradation. Since nitrate was utilized as the nitrogen source in this system, it was included in the model as a limiting substrate (nutrient). A negative affect of excessive accumulation of biomass in the reactor on biofilter performance has also been observed in highly loaded synthetic ...

Mass transport phenomena occurring in the biofilms of gas phase trickle-bed biofilters are investigated in this study. The effect of biofilm structure on mass transfer mechanisms is examined using experimental observation from the operating of biofilters, microelectrode techniques and microscopic examination. Since the biofilms of biofilters used for waste gas treatment are not completely saturated with water, there is not a distinguishable liquid layer outside the biofilm. Results suggest that due to this characteristic, gas phase substrates (such as oxygen or volatile organic compounds) may not be limited by the aqueous phase because transport of the compound into the biofilm can occur directly through non-wetted areas. On the other hand, for substrates that are present only in the liquid phase, such as nitrate, the mass transfer limitation is more serious because of the limited liquid supply. Microscopic observations show that a layered structure with void spaces exists within the biofilm. Oxygenconcentration distributions along the depth of the biofilms are examined using an oxygen microelectrode. Results indicate that there are some high dissolved oxygen zones inside the biofilm, which suggests the existence of passages for oxygen transfer into the deeper sections of the biofilm in a gas phase trickle-bed biofilter. Both the low gas-liquid mass transfer resistance and the resulting internal structure contribute to the high oxygen penetration within the biofilms in gas phase trickle-bed biofilters.

The purpose of this research is to estimate the unknown parameters of a mathematical model of the biodegradation of volatile organic compounds (VOCs) in a gas phase trickle-bed biofilter, using experimental results from a two-reactor pilot-scale system treating the VOC diethyl ether. The model considers a dynamic three-phase system, (biofilm, water, and gas), nonuniform bacterial population, and one limiting substrate. The nonlinear parameter estimation was done in two stages: estimates of the steady-state model parameters were obtained first, and then, these values were used in the estimation of the remaining parameters. Experimentally obtained biofilter performance curves and batch tests were used for the estimation of the steady-state parameters: maximum rate of substrate utilization (μmXf/Y), Monod constant (Ks), and biofilm/water diffusivity ratio for ether, rd. Dynamic biofilter performance data were used to obtain the estimates of the six remaining parameters: yield coefficient (Y). maximum grow...

The objective of this work was to analyze the effect of water content on the removal of volatile organic compounds (VOCs) in gas phase trickle-bed biofilters. Previous studies revealed that excessive accumulation of biomass in the reactor had a negative effect on contaminant removal efficiency. To solve this problem, periodic backwash was used to remove excess biomass and maintain an effective operation. Results showed that the ether removal efficiency dropped immediately after backwashing and gradually improved to reach the optimal value within about 24 hours. The initial drop in performance can be attributed to biological effects, such as loss of active biomass and the necessity for an adaptation period for the microbial culture. However, mass transfer limitations due to the water retained in the reactor may also be important. To investigate the effect of water content on the biofilter performance, an experiment evaluated the effect of draining after backwashing was conducted. Biofilters were allowed to drain for different periods of time before restarting the reactors. A longer lapse time in draining before the restart resulted in better ether removal efficiency. The improvement of biofilter performance after backwashing was explained with a combination of biological and physical effects. A mathematical model was then used to simulate the performance of the biofilter under these conditions and to support the conclusions obtained. The mathematical model considered a three-phase system (biofilm, water, and gas phase), dunamic processes, non-uniform bacterial population, and one limiting substrate.

Rotating drum biofilters (RDBs) are cost-effective for control of emissions of volatile organic compounds (VOCs) from waste gas streams. In this paper, a dynamic mathematical model is presented which simulates and predicts the variation in performance of a multi-layer RDB with time on the basis of the two-film theory. The model takes into account factors including biofilm growth and biomass loss, and a changing biofilm surface area and thickness assuming quasi-steady-state conditions in the two-phase system and uniform bacterial population. Toluene was assumed to be the only rate-limiting substrate. The model equations for the gas-phase mass balance and biofilm growth were solved using MATLAB based on the fourth-fifth-order Runge–Kutta technique, and the concentration profiles in the biofilms were obtained using the method of orthogonal collocation. Simulation results showed that the toluene removal efficiency decreased with increased toluene loading or increased duration of operation of the biofilter. Calculation results were compared to the experimental results, which demonstrated that the dynamic model provided a good simulation of the performance of the biofilter.

Butanol, ether, toluene, and hexane, which have Henry's constants ranging from 0.0005 to 53, were used to investigate the effects of substrate solubility or availability on the removal of volatile organic compounds (VOCs) in trickle-bed biofilters. Results from this study suggest that, although removal of a VOC generally increases with a decrease in its Henry's constant, an optimal Henry's constant range for biofiltration may exist. For the treatment of VOCs with high Henry's constant values, such as hexane and toluene, the transfer of VOCs between the vapor and liquid phases or between the vapor phase and the biofilm is a rate-determining step. However, oxygen (O2) transfer may become a rate-limiting step in treating VOCs with low Henry's constants, such as butanol, especially at high organic loadings. The results demonstrated that in a gas-phase aerobic biofilter, nitrate can serve both as a growth-controlling nutrient and as an electron acceptor in a biofilm for the respiration of VOCs with low Henry's constants. Microbial communities within the biofilters were examined using denaturing gradient gel electrophoresis to provide a more complete picture of the effect of O2 limitation and denitrification on biofilter performance.

2-D HMM methods have recently been applied to handwritten Chinese character recognition(HCCR) with much practical prospect, however, the time consuming is a great obstacle for its widely using. To overcome this weakness a novel block-based ICM algorithm, which will decode image block by block other than pixel by pixel, is proposed. Experiments shows that it can work much better than the traditional one for HCCR with a little higher accuracy and much higher speed of recognition. It offers a great potential for HCCR when using truly-2D HMM.

The objective of this work is to develop a fundamental mathematical model that describes the biodegradation of volatile organic compounds (VOCs) in gas phase trickle-bed biofilters, and to estimate the unknown model parameters. The mathematical model considers a three-phase system (biofilm, water, and gas phase), non-uniform bacterial population, and one limiting substrate. Two pilot-scale trickle-bed biofilters were operated to remove the VOC diethyl ether from a waste gas stream. Experimental results from this system were used to estimate the unknown parameters of the steady-state model: the maximum rate of substrate utilization μ m X f / Y , the Monod constant, K s , and the ether biofilm/water diffusivity ratio, r d . While the value of μ m X f / Y was uniquely determined, the values of K s and r d were highly correlated. High values of the Monod constant and the ether diffusivity in the biofilm gave similar predictions to those corresponding to low values of both parameters. Batch studies were used to estimate the value of K s without mass transfer limitations showing that K s < 1 mg/L=2.6 mg COD/L. Using this information and biofilter operating data the true values of K s and r d were determined.