Igor Bodík

Utilization of Biodiesel By-Products for Biogas Production

This contribution reviews the possibility of using the by-products from biodiesel production as substrates for anaerobic digestion and production of biogas. The process of biodiesel production is predominantly carried out by catalyzed transesterification. Besides desired methylesters, this reaction provides also few other products, including crude glycerol, oil-pressed cakes, and washing water. Crude glycerol or g-phase is heavier separate liquid phase, composed mainly by glycerol. A couple of studies have demonstrated the possibility of biogas production, using g-phase as a single substrate, and it has also shown a great potential as a cosubstrate by anaerobic treatment of different types of organic waste or energy crops. Oil cakes or oil meals are solid residues obtained after oil extraction from the seeds. Another possible by-product is the washing water from raw biodiesel purification, which is an oily and soapy liquid. All of these materials have been suggested as feasible substrates for anaerobic degradation, although some issues and inhibitory factors have to be considered.

Nitrogen removal in an anaerobic baffled filter reactor with aerobic post-treatment.

A new sewage treatment system was studied, which consisted of an anaerobic baffled filter reactor and the following aerobic post-treatment. One of the two studied systems (AN-I) was inoculated with psychrophilic digested sludge, the second one (AN-II) was operated without inoculation. The HRT in anaerobic and aerobic parts of the reactors were about 15 and 4 h, respectively. The temperature in both reactors varied during the year from 4.5 to 23 degrees C. All monitored parameters were removed with relatively high efficiencies (COD = 78.6-83.0%, BOD5 = 92.5-94.0% and SS = 80.9-92.7%). An intensive nitrification process was observed during the whole year in both reactors (under average temperature of 5.9 degrees C in January 2000, also). The average removal of the NH4-N varied during the year from 46.4% to 87.3%. In both systems a partial denitrification process was observed, too.

The use of upflow anaerobic filter and AnSBR for wastewater treatment at ambient temperature

This research was carried out in order to study the effect of the temperature and hydraulic retention time (HRT) on the start-up and steady-state performance of upflow anaerobic filter (UAF) and anaerobic sequencing batch reactor (AnSBR). A mixture of synthetic substrate (glucose and sodium acetate) and real municipal wastewater was used as a laboratory substrate. The temperature (in the range 9-23 degrees C) and HRT (in the range 6-46 h) were selected as the most decisive technological parameters for a practical application. Average removal efficiency of COD found for tested anaerobic reactors were 56-88% (AnSBR) and 46-92% (UAF) depending on used temperature and HRTs. Based on the observed results, the use of AnSBR and UAF in practice seems to be a potential technology for (pre)-treatment of wastewater produced by small communities.

Biodiesel waste as source of organic carbon for municipal WWTP denitrification

This paper presents the results of experiments to test biodiesel waste (glycerine--g-phase) as an organic carbon source for the removal of nitrate in a WWTP denitrification process. Investigation of g-phase was first centered on g-phase utilization as an external source for denitrification under laboratory conditions and consequently, after positive results from the laboratory investigation, g-phase was applied in the denitrification process in the WWTP Vrútky (35,000 PE). This WWTP had insufficient nitrogen removal via denitrification. Denitrification was insufficient due to an influent with a low BOD5/N ratio (1.7:1) entering into the activated sludge tank. Laboratory experiments and calculations showed that, to reach Ntotal concentration under 10 mg l(-1) in effluent, a biodiesel waste dose of 500 kg(COD) d(-1) was necessary. Glycerol phase (g-phase) dosing into the denitrification tank increased denitrification efficiency by 2.0 - 5.0 mg(NO)(3)(-N)l(-1) per 100 l of g-phase dose into the denitrification tank.

National study of illicit drug use in Slovakia based on wastewater analysis

The aim of this study was to analyze illicit drugs and their metabolites in wastewater from eight selected wastewater treatment plants (WWTPs) in Slovakia. The effect of two of the biggest music festivals in Slovakia on illicit drugs in wastewater was also investigated. Urinary bio-markers of amphetamine, methamphetamine, cocaine, cannabis and ecstasy use were analyzed by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). We then compared our results with data obtained in other parts of Europe and the world. This study demonstrates that Slovakia has one of highest methamphetamine consumption rates in Europe. Within Slovakia, the highest level of methamphetamine consumption was found in Petržalka, where the mean specific load of this drug in sewage was 169 mg/day/1000 inhabitants; the next highest loads were detected in Piešťany (128 mg/day/1000 inhabitants) and Bratislava (124 mg/day/1000 inhabitants). Amphetamine, ecstasy and cannabis consumption in our study were comparable to that found in other European cities, whereas cocaine consumption was lower. We also analyzed the pattern of drug consumption over the course of a week. The load of the cocaine metabolite benzoylecgonine in wastewater increased during the weekend. The use of this drug was most common in the capital of Slovakia. Increased consumption was also found during a folk festival in Piešťany. The ecstasy load in wastewater from larger cities also significantly increased over the weekend. An increase of drug consumption was also detected during a music festival in Trenčín, especially for ecstasy. The specific load of ecstasy during this festival increased from 3mg/day/1000 inhabitants to 29 mg/day/1000 inhabitants. The possible influence of music styles on the consumption of certain drugs was also observed. During a folk festival, methamphetamine and cocaine were more commonly used.

Pilot study of seasonal occurrence and distribution of antibiotics and drug resistant bacteria in wastewater treatment plants in Slovakia.

This work presents environmental and quality-control data from the analyses of 33 antibiotics in influent and effluent water from two waste water treatment plants (WWTPs) in the capital and the biggest city of Slovakia. Seeing that consumption of antibiotics depends on epidemiological season, samples were collected during February and August. Among assessed antibiotics ciprofloxacin and clarithromycin were detected in highest concentrations in influent water. Seasonal changes were observed only in plant A when antibiotic concentrations decreased. On the other hand an increase in some cases was observed in plant B. Insufficient degradation of some macrolides, sulfonamides and trimethoprim was detected according to their higher concentrations in effluent water. Contact of antibiotics in subinhibitory concentrations and sludge bacteria in WWTPs represent the base for the development of significant levels of microbial resistance. Simultaneously, antibiotic resistance of fecal coliforms and fecal streptococci from sewage sludge was evaluated. Majority of coliform bacteria were found to be resistant to ampicillin and gentamicin. A significant seasonal difference was determined only in case of high-level resistance. In summer samples, an increase in the strains resistant to concentrations higher than the resistance breakpoints established by EUCAST and NCCLS was observed. No antibiotic resistance in streptococci was observed. However, as a part of sewage sludge is mixed with compost and utilized in agriculture, better processing of sludge should be considered.

Acidobasic balances in the course of heterotrophic denitrification

Abstract Acidobasic balances are discussed to define the influence of organic substrate composition on CO2, HCO−3, CO2−3 production and pH value changes in the course of heterotrophic denitrification. The decisive parameter for these balances for undissociated substrates is average oxidation number of carbon (AONC). For dissociated substrates the balances are influenced by the composition of organic compounds (the number of C, H, O atoms and the oxidation number). The rules for determination of pH value changes according to substrate composition are discussed both for dissimilative and assimilative reactions. The theoretical conclusions are verified in kinetic denitrification tests with selected organic compounds (glucose, glycerine, ethanol, methanol, acetate, endogenous substrate). Furthermore, indication of nitrates and nitrites removal (the end of denitrification) by continuously measured pH is described (when denitrification has been finished, pH value begins to decrease).

Zerovalent iron and iron(VI): Effective means for the removal of psychoactive pharmaceuticals and illicit drugs from wastewaters

Herein we report the analysis of 27 selected psychoactive compounds found in the wastewater of the largest suburb in the eastern part of Central Europe Bratislava—Petržalka, Slovakia. Thirteen of them (MDMA, methamphetamine, amphetamine, THC-COOH, benzoylecgonine, codeine, tramadol, venlafaxine, oxazepam, citalopram, methadone, EDDP, cocaine) were found in concentrations above 30 ng/L. These compoundswere selected for further monitoring. The possibility of complete degradation of these 13 substances by zerovalent iron and iron(VI) was studied in thewastewater from the Petržalka treatment plant. During the week the concentration of themajority of the studied compounds inwastewaterwas stable. Concentrations of MDMA, cocaine, tramadol, and oxazepam reached significantly higher levels during the weekend.Only about 10% removal efficiency for tramadol, venlafaxine, oxazepam, MDMA, citalopram, methadone, and EDDP was observed at the treatment plant. In contrast, methamphetamine, amphetamine, and codeine were removed with 68%, 83%, and 53% efficiency, respectively. The degradation of synthetic drugs (methamphetamine, cocaine, MDMA) in wastewater is limited, while cannabis (of natural biological origin) is degradedwith efficiency greater than 90%. After utilization of the Fenton reaction, its modification, and use of ferrate(VI), a high efficiency of eliminating all of these substances to values below the limit of detection was achieved.

Long-term monodigestion of crude glycerol in a UASB reactor

The aim of this study was to discuss the experience from long-term operation of a laboratory UASB reactor inoculated with suspended or granulated biomass for the treatment of different kinds of crude glycerol in undiluted or diluted state. The UASB reactor was operated under mesophilic conditions. It was demonstrated that the anaerobic treatment of crude glycerol as the only substrate in the UASB reactor is feasible, although the specific inhibition effects and requirements resulting from the nature and composition of the g-phase have to be considered. Deficient concentrations of nutrients had to be compensated by their supplementation into the digester. Long-term microbiological treatment of undiluted crude glycerol led to the process inhibition due to the accumulation of dissolved inorganic salts. When dosing diluted g-phase previously treated by acidulation, very good removal efficiency of COD, stable biogas production and high share of methane in the biogas were observed at the organic loading rates of up to 12kg/(m(3)d).

Anaerobic treatment of biodiesel by-products in a pilot scale reactor

In this work, long-term operation of a pilot scale mixed anaerobic reactor processing crude glycerol and rapeseed meal is discussed. These materials are generated as by-products of biodiesel production. Mixed reactor was operated under mesophilic conditions for the period of 654 days. Total cumulative production of biogas reached 379 m3 (at atmospheric pressure and ambient temperature). Maximum volumetric loading achieved during the operation was 2.17 kg m−3 d−1 for the crude glycerol dose of 2 L. When dosing crude glycerol as a single substrate, average specific production of biogas of 0.76 m3 per L of the g-phase was achieved. The lack of nutrients in the g-phase had to be compensated by an addition of ammonium nitrogen in the form of urea into the reactor. Long term processing of crude glycerol demonstrated that accumulation of dissolved inorganic salts in the reactor can lead to inhibition of the methanogenic activity of microorganisms, causing breakdown of the system. Co-fermentation of crude glycerol with rapeseed meal provided stable biogas production and it was shown to be a feasible way of anaerobic degradation of these substrates. At the maximum volumetric load of 1.33 kg m−3 d−1 (500 mL of g-phase and 500 g of rapeseed meal), the average biogas production reached 0.58 m3 d−1.