Removal of MIB and geosmin using granular activated carbon with and without MIEX pre-treatment

This study assessed the impact of MIEX pre-treatment, followed by either coagulation or microfiltration (MF), on the effectiveness of pilot granular activated carbon (GAC) filters for the removal of the taste and odour compounds, 2-methylisoborneol (MIB) and geosmin, from a surface drinking water source over a 2-year period. Complete removal of MIB and geosmin was achieved by all GAC filters for the first 10 months, suggesting that the available adsorption capacity was sufficient to compensate for differences in dissolved organic carbon (DOC) entering the GAC filters.Reduction of empty bed contact time (EBCT), in all but one GAC filter, resulted in breakthrough of spiked MIB and geosmin, with initial results inconclusive regarding the impact of MIEX pre-treatment. MIB and geosmin removal increased over the ensuing 12 months until complete removal of both MIB and geosmin was again achieved in all but one GAC filter, which had been pre-chlorinated. Autoclaving and washing the GAC filters had minimal impact on geosmin removal but reduced MIB removal by 30% in all but the pre-chlorinated filter, confirming that biodegradation impacted MIB removal. The impact of biodegradation was greater than any impact on GAC adsorption arising from DOC differences due to MIEX pre-treatment. It is not clear whether, at a lower initial EBCT, MIEX pre-treatment may have impacted on the adsorption capacity of the virgin GAC.The GAC filter maintained at the longer EBCT, which was also pre-chlorinated, completely removed MIB and geosmin for the period of the study, suggesting that the greater adsorption capacity was compensating for any decrease in biological degradation.     

Effects of backwashing on the prosobranch snail Potamopyrgus jenkinsi Smith in granular activated carbon (GAC) adsorbers

Granular activated carbon (GAC) adsorbers are often the penultimate stage of surface water treatment and provide ideal habitats for invertebrates. Proliferation of chlorine-resistant invertebrates in GAC adsorbers may lead to their efflux into distribution systems, possibly resulting in contamination of customers' tap water. GAC adsorber sampling and laboratory experiments were undertaken to determine the effects of routine backwashing on GAC adsorber populations of the chlorine-resistant snail Potamopyrgus jenkinsi at a water treatment works. GAC adsorber sampling results suggested that routine backwashing altered the spatial distribution of snails, but not their overall abundance. In small-scale glass columns 40-50% of the smallest (0.3-0.6 mm shell height) juvenile snails were removed by a GAC backwash bed expansion of 30-40%; however, bed expansions of greater than 20% were not possible in the GAC adsorbers.     

Anaerobic dechlorination using a fluidized-bed GAC reactor

A simulated high-strength industrial wastewater containing acetate, phenol, and orthochlorophenol (2-CP) was treated using an anaerobic fluidized-bed granular activated carbon (GAC) reactor. Although carbon replacement was initiated to maintain the effluent quality from the reactor and to minimize the inhibitory effects of 2-CP, the latter phase of this study demonstrated that carbon replacement was not necessary. A large pulse input of organic feed was introduced to investigate the resilience of the reactor to severe and sudden increases in influent organic loading. With appropriate pH adjustment, the reactor stabilized within less than two days. A mathematical model was developed to investigate the interaction between the adsorption and biodegradation of compounds in the reactor during the large pulse input. The model confirmed that the GAC was instrumental in controlling the buildup of 2-CP in the reactor.     

Advanced water treatment with manganese oxide for the removal of 17alpha-ethynylestradiol (EE2)

Municipal wastewater is supposed to be one of the most important sources of endocrine-disrupting compounds (EDCs) in water. Therefore, advanced treatments and cost-efficient techniques should be developed to prevent the spread of this type of pollution into the environment. In this view, experiments were conducted in which the removal of 17alpha-ethynylestradiol (EE2), a synthetic and persistent estrogen, from water was monitored in three upstream bioreactors (UBRs), filled with, respectively, sand, granulated activated carbon (GAC) and MnO(2) granules. Tap water, spiked with 15,000ngEE2/L was filtered through the reactors with a hydraulic retention time of approximately 1h. The removal of EE2 in the sand, GAC and MnO(2) reactors was, respectively, 17.3%,>99.8% and 81.7%. The removal in the GAC reactor was mainly due to adsorption. The MnO(2) reactor, however, removed significantly more EE2 than could be predicted from its adsorption capacity, probably thanks to its catalytic properties. These catalytic properties could make it a cost-efficient technique for the removal of EE2, but further research at more environmentally relevant concentrations is needed.     

Degradation of p-nitrophenol in aqueous solution by microwave assisted oxidation process through a granular activated carbon fixed bed

A microwave (MW) assisted oxidation process was investigated for degradation of p-nitrophenol (PNP) from aqueous solution. The process consisted of a granular activated carbon (GAC) fixed bed reactor, a MW source, solution and air supply system, and a heat exchanger. The process was operated in continuous flow mode. Air was applied for oxygen supply. GAC acted as a MW energy absorption material as well as the catalyst for PNP degradation. MW power, air flow, GAC dose, and influent flow proved to be major factors which influenced PNP degradation. The results showed that PNP was degraded effectively by this new process. Under a given condition (PNP concentration 1330mg/L, MW power 500 W, influent flow 6.4 mL/min, air flow 100 mL/min), PNP removed 90%, corresponding to 80% of TOC removal. The pathway of PNP degradation was deduced based on GC-MS identification of course products. PNP experienced sequential oxidation steps and mineralized ultimately. Nitro-group of PNP converted to nitrite and nitrate. Biodegradability of the solution was improved apparently after treatment by MW assisted oxidation process, which benefit to further treatment of the solution using biochemical method.     

Ecotoxicological assessment of grey water treatment systems with Daphnia magna and Chironomus riparius

In order to meet environmental quality criteria, grey water was treated in four different ways: 1) aerobic 2) anaerobic + aerobic 3) aerobic + activated carbon 4) aerobic + ozone. Since each treatment has its own specific advantages and disadvantages, the aim of this study was to compare the ecotoxicity of differently treated grey water using Chironomus riparius (96 h test) and Daphnia magna (48 h and 21d test) as test organisms. Grey water exhibited acute toxicity to both test organisms. The aerobic and combined anaerobic + aerobic treatment eliminated mortality in the acute tests, but growth of C. riparius was still affected by these two effluents. Post-treatment by ozone and activated carbon completely removed the acute toxicity from grey water. In the chronic toxicity test the combined anaerobic + aerobic treatment strongly affected D. magna population growth rate (47%), while the aerobic treatment had a small (9%) but significant effect. Hence, aerobic treatment is the best option for biological treatment of grey water, removing most of the toxic effects of grey water. If advanced treatment is required, the treatment with either ozone or GAC were shown to be very effective in complete removal of toxicity from grey water.     

Croissance bacterienne sur charbon actif granule. Investigation au microscope electronique a balayage

Recent work characterising biological development in granular activated carbon filters (GAC) has contributed to a better understanding of the role of bacterial growth in the efficiency of adsorption processes in water treatment. Among the techniques involved in biological GAC studies, scanning electron microscopy (SEM) can be used to describe the physical relations between bacterial populations and activated carbon surface. In this study, an effective technique is presented for two-phased fixation (2% paraformaldehyde-2.5% glutaraldehyde and 1% osmium tetroxyde), dehydration and critical point drying of “biological” activated carbon particles. Microscopic examination of GAC after 5 days of filtration (drinking water artificially contaminated with 1,0 mg l⁻¹ of an anionic surfactant) showed the nature of the fixation sites of organic matter and the initially scattered bacterial growth sites. The microbiological colonization appears then along surface crevices and holes (Fig. 1) where substrate concentration occurs and where organisms are shielded from fluid shear forces. Bacteria attach to the carbon surface by secreting a network-like polysaccharide matrix (Fig. 2). After 15 days of filtration (Fig. 3), biological maturation of the carbon induces the progressive formation of a membranous organic film (surfactant precipitation and bioflocculation) making it difficult to observe bacterial development on the carbon surface (Fig. 4). However, there is no evidence that a continuous biofilm (uniform layer of bacteria in a slimy shell) develops around the carbon granules. The observations support the assumption that structural relationships between microorganisms and carbon surface are modified considerably during the accumulation of organic floc and cellular debris. This organic support medium enhances the biodegradation of substrates that would obtained from the carbon surface alone. Therefore, it appears that the effective metabolization of organic adsorbates in GAC filtration units is only slightly connected with the efficiency of physico-chemical adsorption processes.     

Biodegradation of 2-fluorobenzoate and dichloromethane under simultaneous and sequential alternating pollutant feeding

Two up-flow fixed-bed reactors (UFBRs), inoculated with activated sludge and operated for 162 days, were fed 1mmolL(-1)d(-1) with two model halogenated compounds, 2-fluorobenzoate (2-FB) and dichloromethane (DCM). Expanded clay (EC) and granular activated carbon (GAC) were used as biofilm carrier. EC did not have any adsorption capacity for both model compounds tested, whereas GAC could adsorb 1.3mmolg(-1) GAC for 2-FB and 4.5mmolg(-1) GAC for DCM. Both pollutants were degraded in both reactors under simultaneous feeding. However, biodegradation in the EC reactor was more pronounced, and re-inoculation of the GAC reactor was required to initiate 2-FB degradation. Imposing sequential alternating pollutant (SAP) feeding caused starvation periods in the EC reactor, requiring time-consuming recovery of 2-FB biodegradation after resuming its feeding, whereas DCM degradation recovered significantly faster. The SAP feeding did not affect performance in the GAC reactor as biodegradation of both pollutants was continuously observed during SAP feeding, indicating the absence of true starvation.     

Selective removal of 17beta-estradiol at trace concentration using a molecularly imprinted polymer

A molecularly imprinted polymer (MIP) was synthesized with 17beta-estradiol (E2) as template. It was then capable to recover this compound by 100+/-0.6% from a 2 microg/L aqueous solution. By comparison, E2 recoveries of 77+/-5.2%, 87.1+/-2.3% and 19.1+/-7.8%, were achieved using a non-imprinted polymer (NIP) synthesized under the same conditions (but without template), a commercial C18 extraction phase and granular-activated carbon (GAC), respectively. When fluoxetine hydrochloride and acenaphthene were added as interferences to the aqueous solution at 2 microg/L each, E2 was recovered by 95.5+/-4.0% from the MIP, compared to 54.5+/-9.4%, 76.0+/-2% and 14.3+/-0.1% from the NIP, C18 and GAC phases, respectively. Estrogenic activity equivalent to the effect caused by 22.4 ng E2/L was recorded in the MIP extract from a wastewater sample whereas no activity was detected in the NIP extract. This suggested the imprinted polymers removed estrogenic compounds. This study therefore demonstrates the potential of MIPs for the selective removal of endocrine-disrupting compounds. By using a synthetic analogue to natural hormone receptors, adsorption is based on the same property that makes the contaminants harmful. Biological treatment of enriched E2 was also demonstrated.     

Biological treatment of H(2)S using pellet activated carbon as a carrier of microorganisms in a biofilter

Biological treatment is an emerging technology for treating off-gases from wastewater treatment plants. The most commonly reported odourous compound in off-gases is hydrogen sulfide (H(2)S), which has a very low odor threshold. This study aims to evaluate the feasibility of using a biological activated carbon as a novel packing material, to achieve a performance-enhanced biofiltration processes in treating H(2)S through an optimum balance and combination of the adsorption capacity with the biodegradation of H(2)S by the bacteria immobilized on the material. The biofilm was mostly developed through culturing the bacteria in the presence of carbon pellets in mineral media. Scanning electron microscopy (SEM) was used to identify the biofilm development on carbon surface. Two identical laboratory scale biofilters, one was operated with biological activated carbon (BAC) and another with virgin carbon without bacteria immobilization. Various concentrations of H(2)S (up to 125 ppmv) were used to determine the optimum column performance. A rapid startup (a few days) was observed for H(2)S removal in the biofilter. At a volumetric loading of 1600 m(3)m(-3)h(-1) (at 87 ppmv H(2)S inlet concentration), elimination capacity of the BAC (181 gH(2)Sm(-3)h(-1)) at removal efficiency (RE) of 94% was achieved. If the inlet concentration was kept at below 30 ppmv, high H(2)S removal (over 99%) was achieved at a gas retention time (GRT) as low as 2s, a value, which is shorter than most previously reported for biofilter operations. The bacteria population in the acidic biofilter demonstrated capacity for removal of H(2)S in a broad pH range (pH 1-7). There are experimental evidences showing that the spent BAC could be re-used as packing material in a biofilter based on BAC. Overall, the results indicated that an unprecedented performance could be achieved by using BAC as the supporting media for H(2)S biofiltration.     

Discriminating and assessing adsorption and biodegradation removal mechanisms during granular activated carbon filtration of microcystin toxins

Microcystins are cyanobacterial toxins that are problematic for water authorities due to their resistance to conventional water treatment. Granular activated carbon (GAC) filtration has been shown to be effective in removing microcystin from water using both adsorption and biodegradation removal mechanisms; however, little is known regarding which removal mechanism predominates and to what extent. In this study, microcystin removal due to adsorption and biodegradation in GAC filtration were discriminated and assessed by commissioning three parallel laboratory columns, including a sterile GAC column, a conventional GAC column and a sand column. The results demonstrate that biodegradation is an efficient removal mechanism once it commences and that the rate of biodegradation was dependent upon temperature and initial bacterial concentration. Adsorption of microcystins was prevalent during the initial stages of the GAC columns and was modelled using the homogeneous surface diffusion model (HSDM). The HSDM provided evidence that an active biofilm present on the surface of the conventional GAC hindered adsorption of microcystin compared with the sterile GAC with no active biofilm. Up to 70% removal of microcystin-LR was still observed after 6 months of operation of the sterile GAC column, indicating that adsorption still played a vital role in the removal of this toxin.     

颗粒活性炭吸附对预臭氧后微污染原水水质影响研究

在不同的预臭氧浓度条件下处理微污染原水,考察了颗粒活性灰（GAC）吸附对处理后水样水质的影响.选择化学需氧量（CODMn）、溶解性有机碳（DOC）、生物可降解溶解性有机碳（BDOC）、UV254和氨氮（NH;-N）含量及有机物分子量分布作为考察吸附效果的检测指标.结果表明,在静态吸附时间达到5天时,颗粒活性炭吸附曲线开始趋于平缓,吸附时间超过5天之后吸附趋于饱和;预臭氧含量为2.5 mg/L时,颗粒活性炭对有机物的吸附效果最佳,对CODMn、DOC、BDOC的去除率分别为53.2％,63.2％和36.2％;在不同预臭氧处理条件下,颗粒活性炭对NH;-N的吸附效果并未表现出较大的差异,吸附去除率约为5％;颗粒活性炭优先吸附水中分子量＞ 10kDa的有机物,其次为分子量＜1 kDa的有机物.     

Constructed wetland systems vegetated with different plants applied to the treatment of tannery wastewater

Wastewaters from leather processing are very complex and lead to water pollution if discharged untreated, especially due to its high organic loading. In this study the survival of different plant species in subsurface horizontal flow constructed wetlands receiving tannery wastewater was investigated. Five pilot units were vegetated with Canna indica, Typha latifolia, Phragmites australis, Stenotaphrum secundatum and Iris pseudacorus, and a sixth unit was left as an unvegetated control. The treatment performance of the systems under two different hydraulic loading rates, 3 and 6 cmd(-1), was assessed. COD was reduced by 41-73% for an inlet organic loading varying between 332 and 1602 kgha(-1)d(-1) and BOD(5) was reduced by 41-58% for an inlet organic loading varying between 218 and 780 kgha(-1)d(-1). Nutrient removal occurred to lower extents. Phragmites australis and Typha latifolia were the only plants that were able to establish successfully. Despite the high removal of organic content from the influent wastewater, during 17 months of operation, no significant differences in performance were observed between units.     

Evaluation of granular activated carbon technology for the removal of methyl tertiary butyl ether (MTBE) from drinking water

This study evaluated granular activated carbons (GACs) using rapid small-scale column tests (RSSCTs) on methyl tert-butyl ether (MTBE) levels from 20 to 2000 microg/L, with or without the presence of tert-butyl alcohol, benzene, toluene, p-xylene (BTX) in two groundwater (South Lake Tahoe Utility District [Lake Tahoe, CA] and Arcadia Well Field [Santa Monica, CA]) and a surface water source (Lake Perris, CA). Direct comparison between two GACs was made for RSSCTs conducted with surface water from Lake Perris. The impact of natural organic matter on GAC performance was investigated and found to correspond with total organic carbon concentration in the three source waters. Significant reduction in GAC performance for MTBE due to competitive adsorption from soluble fuel components (e.g., BTX) was observed. Little or no difference in GAC usage rate or bed life was detected as the empty-bed contact time is changed from 10 to 20 min for RSSCTs conducted in the two groundwater sources, whereas the RSSCTs conducted in the surface water source exhibited significant increase in GAC usage rate as the empty-bed contact time is decreased from 20 to 10 min. This finding suggests that the higher NOM content of the surface water over the groundwater sources caused a greater competitive-adsorption effect that made more sites on the GAC to be unavailable to MTBE, thus decreasing its rate of adsorption and GAC performance for MTBE. Finally, the impact of differential influent MTBE concentration on GAC performance was demonstrated.     

Fossil organic carbon in wastewater and its fate in treatment plants

This study reports the presence of fossil organic carbon in wastewater and its fate in wastewater treatment plants. The findings pinpoint the inaccuracy of current greenhouse gas accounting guidelines which defines all organic carbon in wastewater to be of biogenic origin. Stable and radiocarbon isotopes (¹³C and ¹⁴C) were measured throughout the process train in four municipal wastewater treatment plants equipped with secondary activated sludge treatment. Isotopic mass balance analyses indicate that 4–14% of influent total organic carbon (TOC) is of fossil origin with concentrations between 6 and 35 mg/L; 88–98% of this is removed from the wastewater. The TOC mass balance analysis suggests that 39–65% of the fossil organic carbon from the influent is incorporated into the activated sludge through adsorption or from cell assimilation while 29–50% is likely transformed to carbon dioxide (CO₂) during secondary treatment. The fossil organic carbon fraction in the sludge undergoes further biodegradation during anaerobic digestion with a 12% decrease in mass. 1.4–6.3% of the influent TOC consists of both biogenic and fossil carbon is estimated to be emitted as fossil CO₂ from activated sludge treatment alone. The results suggest that current greenhouse gas accounting guidelines, which assume that all CO₂ emission from wastewater is biogenic may lead to underestimation of emissions.     

Occurrence and treatment of wastewater-derived organic nitrogen

Dissolved organic nitrogen (DON) derived from wastewater effluent can participate in reactions that lead to formation of nitrogenous chlorination by-products, membrane fouling, eutrophication, and nitrification issues, so management of DON is important for both wastewater reuse applications and nutrient-sensitive watersheds that receive discharges from treated wastewater. This study documents DON occurrence in full-scale water/wastewater (W/WW) treatment plant effluents and assesses the removal of wastewater-derived DON by several processes (biodegradation, coagulation, softening, and powdered activated carbon [PAC] adsorption) used for advanced treatment in wastewater reuse applications. After varying levels of wastewater treatment, the dominant aqueous nitrogenous species shifts from ammonia to nitrate after aerobic processes and nitrate to DON in tertiary treatment effluents. The fraction of DON in total dissolved nitrogen (TDN) accounts for at most 52% in tertiary treated effluents (median = 13%) and 54% in surface waters impacted by upstream wastewater discharges (median = 31%). The 5-day biodegradability/bioavailability of DON (39%) was higher, on average, than that of dissolved organic carbon (DOC, 26%); however, upon chlorination, the DON removal (3%) decreased significantly. Alum coagulation (with ≥8 mg/L alum per mg/L DOC) and lime softening (with pH 11.3-11.5) removed <25% of DON and DOC without selectivity. PAC adsorption preferentially removed more DOC than DON by 10% on average. The results provided herein hence shed light on approaches for reducing organic nitrogen content in treated wastewater.     

Fate of natural estrogens in batch mixing experiments using municipal sewage and activated sludge

Since natural estrogens such as 17beta-estradiol (E2) and estrone (E1) are excreted daily by humans, E2 and E1, which are classified as inevitable endocrine-disrupting chemicals, are always present in sewage wastewater. For several years, the monitoring and removal of natural estrogens at sewage treatment plants have been examined by many investigators. However, little is known regarding the exact behavior of estrogens in actual sewage when in contact with activated sludge. In this study, the fate of E2 and E1 as a result of adsorption and decomposition in batch mixing experiments using municipal wastewater and activated sludge collected from an actual municipal sewage treatment plant was investigated. Estrogen concentrations were determined using an enzyme-linked immunosorbent assay (ELISA) kit. E2 and E1 in sewage were removed from the liquid phase in contact with activated sludge, and E2 and E1 adsorbed on the sludge were decomposed in 4h. Significant changes in the adsorption and decomposition of E2 and E1 on the sludge were not observed at low temperatures or when different sludge samples were used such as those acclimatized to low-loading and high-loading conditions. In contrast, the processes leading to the removal of estrogens, such as the adsorption and decomposition of estrogens in contact with activated sludge, were inactivated by sterilizing the sludge. Natural estrogens adsorb onto the activated sludge, and are therefore easy to be biodegraded. In a biological reaction process, therefore, the estrogens will be rapidly removed at the initial stage, when the sewage is satisfactorily mixed with the sludge.     

Biosolids accumulation and biodegradation of domestic wastewater treatment plant sludge by developed liquid state bioconversion process using a batch fermenter

The biosolids accumulation and biodegradation of domestic wastewater treatment plant (DWTP) sludge by filamentous fungi have been investigated in a batch fermenter. The filamentous fungi Aspergillus niger and Penicillium corylophilum isolated from wastewater and DWTP sludge was used to evaluate the treatment performance. The optimized mixed inoculum (A. niger and P. corylophilum) and developed process conditions (co-substrate and its concentration, temperature, initial pH, inoculum size, and aeration and agitation rate) were incorporated to accelerate the DWTP sludge treatment process. The results showed that microbial treatment of higher strength of DWTP sludge (4% w/w of TSS) was highly influenced by the liquid state bioconversion (LSB) process. In developed bioconversion processes, 93.8 g/kg of biosolids was enriched with fungal biomass protein of 30 g/kg. Enrichment of nutrients such as nitrogen (N), phosphorous (P), potassium (K) in biosolids was recorded in 6.2% (w/w), 3.1% (w/w) and 0.15% (w/w) from its initial values of 4.8% (w/w), 2.0% (w/w) and 0.08% (w/w) respectively after 10 days of fungal treatment. The biodegradation results revealed that 98.8% of TSS, 98.2% of TDS, 97.3% of turbidity, 80.2% of soluble protein, 98.8% of reducing sugar and 92.7% of COD in treated DWTP sludge supernatant were removed after 8 days of microbial treatment. The specific resistance to filtration (SRF) in treated sludge (1.4x10(12) m/kg) was decreased tremendously by the microbial treatment of DWTP sludge after 6 days of fermentation compared to untreated sample (85x10(12) m/kg).     

Similarities in effluent organic matter characteristics from Connecticut wastewater treatment plants

Effluent organic matter (EfOM) from five Connecticut (USA) municipal wastewater treatment plants was isolated with DAX8 (hydrophobic fraction) and XAD4 (transphilic fraction) resins. Isolate recoveries ranged from 18 to 42% of the total organic carbon for DAX8 resin and from 6 to 12% for XAD4 resin. Isolated EfOM was characterized by traditional organic geochemistry techniques. Weight-averaged molecular weights of extracted EfOM by size exclusion chromatography were 450-670 Da with higher weights observed for the hydrophobic fractions than the transphilic fractions. Fluorescence characterization showed both humic- and fulvic-like fluorescence, as well as tryptophan- and tyrosine-like fluorescence, the latter not commonly observed for terrestrial organic matter. Fluorescence indices were between 1.5 and 1.9 with lower values observed for hydrophobic EfOM fractions than for transphilic fractions. Specific ultraviolet absorbance was measured between 0.8 and 3.0 L mg⁻¹ m⁻¹ with higher values for the hydrophobic EfOM fractions. Together these results indicated that isolated EfOM is similar in characteristics to microbially derived organic matter from natural aquatic systems. Little variation in EfOM characteristics was observed between the five wastewater treatment plants, suggesting that the characteristics of EfOM are similar, regardless of treatment plant design.     

Treatment of fish-processing wastewater by co-culture of Candida rugopelliculosa and Brachionus plicatilis

This research was conducted as a part of the continuous development of a novel technique for managing fish-processing wastewater by cultivating proteolytic yeast, Candida rugopelliculosa, as possible diet of the rotifer, Brachionus plicatilis. It was feasible to use Alaska Pollack processing wastewater as a growth medium for C. rugopelliculosa, which was stimulatory for growth of the rotifer by 18.3% over the commercial diet of Saccharomyces cerevisiae. Maximum growth of C. rugopelliculosa and reduction of influent soluble chemical oxygen demand (SCOD) concentration were respectively (6.09+/-0.04)x10(6) cells/ml and 70.0% at 6.3h hydraulic retention time (HRT).Method of 4th order Runge-Kutta approximation was successfully applied to determine the Monod kinetics of C. rugopelliculosa by using unsteady state data from only one continuous unsteady state operation at a fixed HRT. The maximum microbial growth rates, mu(max), and half saturation coefficient, K(s), were determined to be 0.82+/-0.22 h(-1) and 690+/-220 mg SCOD/L, respectively. The microbial yield coefficient, Y, and microbial decay rate coefficient, k(d), were determined to be (1.39+/-0.22)x10(4) cells/mg SCOD and 0.06+/-0.01 h(-1), respectively.