Determination of kinetic constants for a two-stage anaerobic upflow packed-bed reactor for dairy wastewater

A two-stage upflow packed-bed (reactors in series) system was used for the treatment of dairy wastewater. Nylon pads were used as supporting media for the biomass. This investigation aimed at the determination of various kinetic constants for substrate, biomass and biogas based on various models. The maximum loadings that could be applied to reactor I and reactor II were 14·29 and 5·0 kg of chemical oxygen demand (COD) per m³ per day, respectively. The maximum COD removal efficiencies at various loading rates were in the ranges of 93·8–98·5% and 72·5–84% for the two reactor systems, respectively. The combined biogas yield was between 0·196 and 0·386 m³ gas/kg COD_a.     

Biodegradation, decolourisation and detoxification of textile wastewater enhanced by advanced oxidation processes

Recently, an increasing application of so called advanced oxidation processes (AOPs) to industrial wastewater has been observed. In particular, an integrated approach of biological and chemical treatment of wastewater is advantageous conceptually. The subject of our study was synthetic wastewater, simulating effluents from knitting industry. The wastewater contained components that are very often used in Polish textile industry: an anionic detergent Awiwaz KG conc., a softening agent Tetrapol CLB and an anthraquinone dyestuff-Acid Blue 40, CI 2125. The toxicity of the detergents and the dye was determined in terms of effective concentration EC50 using mixed cultures of activated sludge as well as pure culture of luminescent bacteria Vibrio fischerii NRRLB-11177. The dye did not undergo biodegradation without AOPs pretreatment, therefore a degree of its removal (decolourisation) by the AOPs has been determined and its bio-sorption properties on the flocks of activated sludge have been studied. The dye adsorption onto flocks of activated sludge was described by Henry's isotherm. Our investigations focussed on the influence of various oxidants like O3, H2O2 and UV light on biodegradation of single components aqueous solution as well as of the whole textile wastewater. The results of kinetic measurements of the biodegradation (by means of acclimated activated sludge) was described by Monod type of kinetic equation. The experimental evidence of the positive effect of chemical oxidation pretreatment on the biodegradation of recalcitrant compounds was quantified by estimation of the kinetic parameters of the Monod equation. Due to the AOPs pretreatment a decrease of the Monod constant and an increase of maximal specific growth rate was observed. The activity of degradative enzymes of activated sludge was assayed by the methods of 2-[4-iodophenyl]-3-[4-nitrophenyl]-5-phenyltetrazolium chloride test.     

Pretreatment of textile dyeing wastewater using an anoxic baffled reactor

A study on pretreatment of textile dyeing wastewater was carried out using an anoxic baffled reactor (ABR) at wastewater temperatures of 5-31.1 degrees C. When hydraulic retention time (HRT) was 8h, the color of outflow of ABR was only 40 times at 5 degrees C and it could satisfy the professional discharge standard (grade-1) of textile and dyeing industry of China (GB4287-92). The total COD removal efficiency of ABR was 34.6%, 47.5%, 50.0%, 53.3%, 54.7% and 58.1% at 5, 9.7, 14.9, 19.7, 23.5 and 31.1 degrees C, respectively. Besides, after the wastewater being pre-treated by ABR when HRT was 6h and 8h, the BOD5/COD value rose from 0.30 of inflow to 0.46 of outflow and from 0.30 of inflow to 0.40 of outflow, respectively. Experimental results indicated that ABR was a very feasible process to decolorize and pre-treat the textile dyeing wastewater at ambient temperature. Moreover, a kinetic simulation of organic matter degradation in ABR at six different wastewater temperatures was carried through. The kinetic analysis showed the organic matter degradation was a first-order reaction. The reaction activation energy was 19.593 kJ mol(-1) and the temperature coefficient at 5-31.1 degrees C was 1.028.     

Potential of combined fungal and bacterial treatment for color removal in textile wastewater

Low efficiency of dye removal by mixed bacterial communities and high rates of dye decolorization by white-rot fungi suggest a combination of both processes to be an option of treatment of textile wastewaters containing dyes and high concentrations of organics. Bacteria were able to remove mono-azo dye but not other chemically different dyes whereas decolorization rates using Irpex lacteus mostly exceeded 90% within less than one week irrespective of dye structure. Decolorization rates for industrial textile wastewaters containing 2-3 different dyes by fungal trickling filters (FTF) attained 91%, 86%, 35% within 5-12 d. Sequential two-step application of FTF and bacterial reactors resulted in efficient decolorization in 1st step (various single dyes, 94-99% within 5 d; wastewater I, 90% within 7 d) and TOC reduction of 95-97% in the two steps. Large potential of combined use of white-rot fungi and traditional bacterial treatment systems for bioremediation of textile wastewaters was demonstrated.     

Mountain cheese factory wastewater treatment with the use of a hybrid constructed wetland

This paper describes the activity period of an experimental hybrid wetland system placed in a cold climate region. The aim is to determine the efficiency of the system in reducing TSS, BOD₅, COD and other pollutants. The constructed wetland consists of a fat-removal unit and a basin for the storage and the distribution of the wastewater which precedes three phytoremediation beds: the first two are parallel and they work as submerged vertical flow wetland with gravel medium for an area of 180 m²; the last is a submerged horizontal flow wetland with sand medium and an area of 360 m². The CW was designed to process a total estimated BOD₅ loading rate of about 24 g m⁻² d⁻¹, which was less than half of the average actual loading rate. The wastewater treatment did not meet the required Italian law outflow limits, most likely due to BOD₅ overloading.     

Bio-kinetic analysis on treatment of textile dye wastewater using anaerobic batch reactor

An anaerobic digestion technique was applied to textile dye wastewater aiming at the colour and COD removal. Pet bottles of 5 L capacity were used as reactor which contains methanogenic sludge of half a liter capacity which was used for the treatment of combined synthetic textile dye and starch wastewater at different mixing ratios of 20:80, 30:70, 40:60, 50:50 and 60:40 with initial COD concentrations as 3520, 3440, 3360, 3264 and 3144 mg L⁻¹, respectively. The reactor was maintained at room temperature (30 ± 3 °C) with initial pH of 7. The maximum COD and colour removal were 81.0% and 87.3% at an optimum mixing ratio of 30:70 of textile dye and starch wastewaters. Both Monod’s and Haldane’s models were adopted in this study. The kinetic constants of cell growth under Haldane’s model were satisfactory when compared to Monod’s model. The kinetic constants obtained by Haldane’s model were found to be in the range of μ_max = 0.037-0.146 h⁻¹, K_s = 651.04-1372.88 mg L⁻¹ and K_i = 5681.81-18727.59 mg L⁻¹.     

Determination of aerobic biodegradation kinetics of olive oil mill wastewater

Aerobic biological treatment was conducted for the treatment of high strength olive oil mill wastewater (OMW). Two different approaches were used for kinetic modeling of OMW biodegradation. TOC removal and CO₂–C evolution were monitored in an open and a closed bioreactor systems, respectively. Gompertz, Refractory organics plus first-order (RFO) and Chen–Hashimoto equations were applied to estimate the kinetic parameters by using the data from bioreactors. Furthermore, change in oxidation stage of carbon was monitored and temperature dependency of OMW biodegradation was investigated based on activation energy. At room temperature, 64% of TOC was removed in the open bioreactor while cumulative CO₂–C evolution was 6.32 g L⁻¹ in closed the bioreactor. Higher biodegradation efficiency and kinetic parameters were obtained at 25 °C rather than 10 °C. Gompertz and RFO equations provided better fitting with CO₂–C and TOC data, respectively. Experimental and kinetic estimations indicated that OMW constituted of approximately 30% refractory organics. The comparison of two different modeling approaches showed that kinetic modeling based on CO₂–C provided better correlation with the experimental data. Temperature coefficient indicated that biological degradation of OMW is slightly dependent on temperature.     

Textiles wastewater treatment using anoxic filter bed and biological wriggle bed-ozone biological aerated filter

In this study, the performance of the anoxic filter bed and biological wriggle bed-ozone biological aerated filter (AFB-BWB-O₃-BAF) process treating real textile dyeing wastewater was investigated. After more than 2 month process operation, the average effluent COD concentration of the AFB, BWB, O₃-BAF were 704.8 mg/L, 294.6 mg/L and 128.8 mg/L, with HRT being 8.1-7.7 h, 9.2 h and 5.45 h, respectively. Results showed that the effluent COD concentration of the AFB decreased with new carriers added and the average removal COD efficiency was 20.2%. During operation conditions, HRT of the BWB and O₃-BAF was increased, resulting in a decrease in the effluent COD concentration. However, on increasing the HRT, the COD reduction capability expressed by the unit carrier COD removal loading of the BWB reactor increased, while that of the O₃-BAF reactor decreased. This study is a beneficial attempt to utilize the AFB-BWB-O₃-BAF combine process for textile wastewater treatment.     

Inhibiting effect of textile wastewater on the activity of sludge from the biological treatment process of the activated sludge plant

Textile industry represents an important source of toxic substances rejected in environment. Indeed, effluent of these industries contains dyes and chemicals. They are rejected in environment without any treatment. The aim of this work is to evaluate ecotoxicological effect of industrial textile effluents on the sludge harvested from activated sludge treatment plant of Marrakech city (Morocco). For this, we are interested in determining the inhibition condition that corresponds to 50% decrease of bacterial activity in sludge. Obtained results showed that inhibition percentage of bacterial activity depends narrowly on contact time and on added effluent volume, until a limit concentration where there is no degradation of substratum. In fact, substratum degradation speed shows about 65 times decrease when 80% (v/v) of textile wastewater is added, in comparison with the controlled one. Consequently the inhibition constant (Ki) that corresponds to 50% of bacterial inhibition activity is estimated to 0.65 mg l^?1 of dye. These studies confirm a real ecotoxicological risk of these effluents. Therefore, a treatment is mandatory before their rejection in environment.     

Use of the Static Granular Bed Reactor (SGBR) with anaerobic sludge to treat poultry slaughterhouse wastewater and kinetic modeling

Poultry slaughterhouses discharge very high amount of wastewaters and these wastewaters can be treated successfully at a very low cost using anaerobic treatment. In this study, the Static Granular Bed Reactor (SGBR), a newly developed anaerobic process which is fully anaerobic granule, and another Static Granular Bed Reactor containing both anaerobic granular biomass and non-granular biomass were employed for the treatment of poultry slaughterhouse wastewater. The objective of the use of two reactors having different types of anaerobic biomass is to evaluate whether anaerobic sludge could be used effectively instead of anaerobic granule, which is much more difficult to obtain than the other during the start up period. Average COD removal efficiencies were greater than 95% for both of the reactors. Furthermore, Grau second-order and modified Stover–Kincannon models were successfully used to develop a kinetic model of the experimental data with a high correlation coefficient (R² > 0.95).     

微生物分子生态学技术在污水处理系统中的应用

微生物分子生态学作为分子生物学与微生物生态学交叉而形成的学科,在污水处理方面广泛应用。本文从分子生态学实验技术角度,综述了目前污水处理系统中微生物群体结构、多样性及其与功能相关性的研究进展,探讨了分子生态学技术的发展与应用前景,并指出研究该体系微生物对于认识微生物系统发育地位具有重要意义。     

White‐rot fungi combined with lignite granules and lignitic xylite to decolorize textile industry wastewater

The feasibility of using immobilized fungi to decolorize textile industry wastewater containing dyes was examined in experiments with: two species of white‐rot fungi (a Marasmius species from Indonesia, which produces copious biomass, and Trametes hirsuta, which produces high levels of laccase); two types of lignite products as adsorbents and solid substrates (lignitic xylite and lignite granules); and four simulated wastewaters, each containing a different kinds of reactive textile azo dye. The growth, extracellular enzyme production, dye degradation and dye absorption parameters afforded by each permutation of fungus, substrate and dye were then measured. Both fungal species grew poorly on xylite, but much better on lignite granules. Marasmius sp. produced up to 67 U/L laccase on lignite granules, but just 10 U/L on xylite, and no other detectable extracellular enzymes. T. hirsuta produced 1343 U/L laccase and up to 12 U/L unspecific peroxidase when immobilized on lignite granules, and 898 U/L laccase with 14 U/L unspecific peroxidase when immobilized on xylite. The amount of color lost from the dye solutions depended on both the type of dye and the enzyme levels in the fermenter.     

Functional stability of a hybrid anaerobic digester/microbial fuel cell system treating municipal wastewater

A thermophilic anaerobic digester (AD) was combined with a microbial fuel cell (MFC) to evaluate whether either component had increased stability when operated in combination as a hybrid system, perturbed by the addition of acetic acid. The MFC and the anaerobic digester were able to operate effectively together. The MFC was more susceptible to high acetic acid load than the AD. The hybrid system did not have increased resilience compared to the solitary systems in the conditions tested. However, the low pH had a relatively delayed effect on the MFC compared to the AD, allowing the hybrid system to have a more stable energy output. Also, at very low pH, when operating as a hybrid, the AD component was able to recover pH to normal levels when the MFC component failed. These results demonstrate that there are synergies that can be gained from this hybrid system.     

A two-stage biological treatment system for ammonium-nitrate-laden wastewater

A two-stage non-conventional bench scale biological treatment system was investigated for the treatment of the wastewater laden with ammonium nitrate. The first stage which consisted of a fixed film anoxic reactor effected denitrification of nitrate ion, while the second stage consisting of a pond effected ammonia removal. Dissimilatory denitrification requires external carbon source as an electron donor. Methanol was used as electron donor in this system. The system exhibited substantial nitrate and ammonia removal. The influent nitrate-N concentration which was on average 193.87 ± 12.68 mg/l was reduced to 5.86 ± 4.86 mg/l in the denitrification unit. There was only a marginal reduction of ammonia in the denitrification unit and most of the ammonia-N was removed in the pond. The ammonia-N was reduced from an average value of 104.87 ± 3.49 mg/l at denitrification unit inlet to 33.37 ± 8.12 mg/l at the pond outlet. There was no corresponding increase in the nitrite or nitrate concentration in proportion to ammonia reduction in the pond. The average nitrate concentration in the pond outlet was 2.4 ± 0.93 mg/l. Microbiological investigation of the system revealed the presence of significant populations of denitrifying organisms in the first stage, and denitrifying, nitrifying and algal populations in the second stage. The system also sustained wastewater of pH as low as 3.87 and appears to be very promising for larger scale industrial wastewater treatment.     

Determination of the kinetic constants of inhibited acetyl cholinesterase

A method for the determination of kinetic constants of inhibited acetylcholinesterase, in the presence of substrate, is proposed. Theoretical, experimental and data treatment aspects are described for a suitable analysis of inhibitors acting with one or two steps. Limitations of other methods recently reported are pointed out.     

The role of sulphidogenesis in anaerobic treatment phase of tannery wastewater treatment in advanced integrated wastewater pond system

An outdoor experiment was conducted to study the competitionbetween Sulphate Reducing Bacteria (SRB) and Methanogenic Archaea (MA) in anaerobictreatment phase of tannery wastewater treatment in pilot-scale Advanced FacultativePond (AFP). The relative electron flow towards sulphate reduction was higher (59–83%) than towardsmethanogenesis (17–41%), although the COD recovery within thereactor varied between 15 and 90%. The results also demonstrated that the flow of electrons towards SRBincreased with increase of the sulphate concentration and decrease of the COD : SO₄ ⁼ ratio.     

A novel spectrophotometric method for determination of kinetic constants of aldehyde oxidase using multivariate calibration method

Although phenanthridine has been frequently used as a specific substrate for the assessment of aldehyde oxidase activity, the use of this method is questionable due to a lower limit of detection and its validity for kinetic studies. In the present study, a novel sensitive multivariate calibration method based on partial least squares (PLS) has been developed for the measurement of aldehyde oxidase activity using phenanthridine as a substrate. Phenanthridine and phenanthridinone binary mixtures were prepared in a dynamic linear range of 0.1–30.0 μM and the absorption spectra of the solutions were recorded in the range of 210–280 nm in Sorenson's phosphate buffer (pH 7.0) containing EDTA (0.1 mM). The optimized PLS calibration model was used to calculate the concentration of each chemical in the prediction set. Hepatic rat aldehyde oxidase was partially purified and the initial oxidation rates of different concentrations of phenanthridine were calculated using the PLS method. The values were used for calculating Michaelis–Menten constants from a Lineweaver–Burk double reciprocal plot of initial velocity against the substrate concentration. The limits of detection for phenanthridine and phenanthridinone were found to be 0.04 ± 0.01 and 0.03 ± 0.01 μM (mean ± SD, n = 5), respectively. Using this method, the K_m value for the oxidation of phenanthridine was calculated as 1.72 ± 0.09 μM (mean ± SD, n = 3). Thus, this study describes a novel spectrophotometric method that provides a suitable, sensitive and easily applicable means of measuring the kinetics of phenanthridine oxidation by aldehyde oxidase without the need for expensive instrumentation.     

污水地下渗滤系统脱氮效果及动力学过程

建立了模拟污水地下渗滤过程的中试系统,重点考察了水力负荷对系统脱氮效率的影响情况,建立了描述地下渗滤系统微生物脱氮过程的动力学模型.结果表明:地下渗滤系统脱氮效果好,抗水力负荷冲击能力强,处理最佳水力负荷0.125m3· m-2· d-1,出水中氮浓度低于《城市污水再生利用——景观环境用水水质》标准( GB/T 18921-2002).地下渗滤系统硝化过程符合一级动力学模型NE=Noe-0.4812t,温度是影响硝化速率的主要因素,两者的关系是KT=0.2218×1.035(T-20);出水硝态氮浓度与水力停留时间之间呈负指数关系,可描述为C=16.3475e-0.2548t,碳源是引起反硝化速率变化的主要因子.在基质层垂直深度65 cm处二次补加生活污水,反硝化速率常数由0.0355提高到0.0488.强调地下渗滤系统的污水净化功能而忽视其生态服务功能,是系统运行中普遍存在的认识误区,过高的水力负荷不利于硝化-反硝化反应的顺利进行.地下渗滤系统运行应采取适宜的水力负荷方式,促进硝化-反硝化作用.