Stanislaw Ledakowicz

Trends in NOx abatement: a review.

Implementation of stringent regulations of NO(x) emission requires the development of new technologies for NO(x) removal from exhaust gases. This article summarizes current state of NO(x) abatement strategy. Firstly, the influence of NO(x) on environment and human health is described. The main focus is put on NO(x) control methods applied in combustion of fossil fuels in power stations and mobile vehicles, as well as methods used in chemical industry. Furthermore the implementation of ozone and other oxidizing agents in NO(x) oxidation is emphasized.

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 Henrys 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.

Influence of pretreatment with Fenton's reagent on biogas production and methane yield from lignocellulosic biomass.

Biomass from Miscanthus giganteus, Sida hermaphrodita and Sorghum Moensch was treated with Fentons reagent for 2 hours under optimal conditions (pH=3, mass ratio of [Fe(2+)]:[H(2)O(2)] equals 1:25 for Miscanthus and Sorghum and 1:15 for Sida). The degrees of delignification were 30.3%, 62.3% and 48.1% for the three plant species, respectively. The volatile fatty acids concentration after chemical pretreatment was high enough for production of biogas with a high methane content. Combined chemical oxidation and enzymatic hydrolysis with cellulase and cellobiase led to glucose contents of above 4 g/L. Among the tested plants, the highest biogas production (25.2 Ndm(3)/kg TS fed) with a 75% methane content was obtained with Sorghum Moensch. The results of the three-step process of biomass degradation show the necessity of applying a chemical pretreatment such as oxidation with Fentons reagent. Moreover, the coagulation of residual Fe(3+) ions is not required for high biogas production.

Integration of nanofiltration and biological degradation of textile wastewater containing azo dye

The anaerobic biological azo dyes reduction process was successfully applied to decolourization of the concentrates from the nanofiltration treatment of real textile effluents. The anaerobic phase was followed by aerobic oxidation aimed at the destruction of the aromatic amine released from azo dye. In the first experiment sequential batch reactor (SBR) combining both the anaerobic and aerobic phase in one unit was used. In the second one the anaerobic stage was separated from the aerobic one. The anaerobic phase fulfilled its aim (decolourization) in both systems (over 90%). In opposite, the aromatic amine was completely degraded in the aerobic reactor (two-sludge system), whereas the orthanilic acid was not degraded (during the aerobic phase) in SBR reactor. The COD reduction was also higher in the two-sludge system than in SBR.

Degradation of household biowaste in reactors.

Household derived biowaste was degraded by biological methods. The system involves the combined method of low-solids (up to 10% w/v of total solids (TS)) anaerobic digestion and aerobic degradation for the recovery of energy (biogas) and the production of fine humus-like material which can be used as a soil amender or a substrate for further thermal treatment (pyrolysis, gasification). The performance of batch and continuous processes carried out in bioreactors (stirred tank reactor, air-lift) of working volume 6 and 18 dm(3), at different temperatures (25-42 degrees C) was monitored by reduction of TS, volatile solids, chemical oxygen demand, total organic carbon, C/N in time. The application of continuous process with recirculation (33%) caused that for residence time of 8-16 h the obtained degree of organic load reduction was similar to that obtained after 72-96 h of the batch process. The experimental data of batch aerobic degradation was also subjected to kinetic analysis. The sequence of the two processes: aerobic and anaerobic or anaerobic and aerobic showed that the degree of organic load reduction was similar in both cases, while the amount of produced biogas was four times higher when the first stage was anaerobic. The final product after dewatering was subjected to pyrolysis and gasification. The gases obtained were characterised by a high heat of combustion of about 11-15 MJ Nm(-3).

Laboratory Simulation of Anaerobic Digestion of Municipal Solid Waste

Abstract Landfill processes were simulated in lab-scale bioreactors—lysimeters. The changes in leachate characteristics as well as the influence of the leachate recirculation on the processes taking place in the landfill were investigated. Lysimeters were filled with material simulating municipal waste in the city of Lodz, Poland. Compost in the amount of 30% w/w and the methanogens inoculum were added in order to enhance a development of methanogenic phase. Leachate produced in lysimeters was recirculated once, twice a week, or everyday. The leachate composition and biogas changes showed trends confirming that the bench-scale lysimeters appeared suitable to simulate processes taking place in the landfill. It was also proved that leachate recirculation accelerate these processes.

Physiological, morphological and kinetic aspects of lovastatin biosynthesis by Aspergillus terreus

This review focuses on selected aspects of lovastatin biosynthesis by Aspergillus terreus. Biochemical issues concerning this process are presented to introduce polyketide metabolites, in particular lovastatin. The formation of other than lovastatin polyketide metabolites by A. terreus is also shown, with special attention to (+)‐geodin and sulochrin. The core of this review discusses the physiology of A. terreus with regard to the influence of carbon and nitrogen sources, cultivation broth aeration and pH control strategies on fungal growth and product formation. Attention is paid to the supplementation of cultivation media with various compounds, namely vitamins, methionine, butyrolactone I. Next, the analysis of fungal morphology and differentiation of A. terreus mycelium in relation to both lovastatin and to (+)‐geodin formation is conferred. Finally, the kinetics of the process, in terms of associated metabolite formation with biomass growth is discussed in relation to published kinetic models. The review concludes with a list of the most important factors affecting lovastatin and (+)‐geodin biosynthesis.

Biodrying of Organic Fraction of Municipal Solid Wastes

The effect of air flow rate on the change of biomass (organic waste material) temperature and moisture content during an autothermal drying process is discussed. The laboratory-scale experiments were performed using a 240-dm3 horizontal composting reactor equipped with an air supply system, biomass temperature measuring system, and air humidity and temperature sensors. An organic fraction of municipal solid waste with the addition of a structural material was used as a substrate in this process. As a result of the autothermal biodrying process, the initial moisture content of organic waste ranging from 0.8 to 0.9 kgH2O/kg of raw waste mass decreased by 50%. Water balances were calculated before and after biodrying, and the difference was less than 10%. The heat of combustion and the calorific value of dried wastes ranged respectively from 6,750 to 12,280 kJ/kg and from 8,050 to 10,980 kJ/kg. The biodrying efficiency varied from 0.73 to 0.97, depending on process conditions. Energy balances showed that average biological energy production rates varied between 1.66 and 6.90 W/kg of raw waste mass.

Co-digestion of agricultural and industrial wastes

The efficiency of anaerobic digestion process is dependent on the type and composition of the material to be digested. This work examines the co-digestion of corn silage, beet pulp silage, carrot residues, and cheese whey in different configurations together with a glycerin fraction — the waste product of transestrification of oils (biodiesel production) in a 25 L bioreactor operated mesophically in a quasi-continuous mode. Co-digestion of corn silage with carrot residues appeared to be more effective than that with cheese whey resulting in the gas production rate equal to 5.9 L L−1 d−1 and 1.4 L L−1 d−1, respectively. The performed experiments showed that a combination of three substrates: corn silage, cheese whey, and glycerin fraction resulted in the highest methane content equal to 61 % and the biogas production rate of 1.8 L L−1 d−1.

Stoichiometry of the aerobic biodegradation of the organic fraction of municipal solid waste (MSW).

An elemental analysis was applied to describe the composition ofthe organic fraction of municipal solid waste (MSW). The initial elemental composition was constant at5H8.5O4N0.2. The changes of the composition during the biodegradation process and the final waste composition were strictly dependent on the process conditions. The decrease in carbon content due to biodegradation increased with temperature at which the experiments were conducted, from 20% at20 °C to about 40% at 37–42 °C after 96 hours. It was correlatedwith the amount of oxygen that was utilised in the investigated processes of aerobicbiodegradation of the waste suspension. The amount of oxygen required for biodegradation of organic fraction of MSW was estimated on the basis of stoichiometric equations and increased from 0.92 moles per 1 mole of waste at 20 °C to 1.6 moles at 42 °C within 96 hours of the experiments.