Acta Facultatis Ecologiae - Technická univerzita vo Zvolene

70microorganisms to [9]. Although microbial deteriorationof MWFs is a problem, such deteriorationcan be used to advantage for the disposal of operationallyexhausted fluids. There is growing interest inexploiting the biocatalytic potential of micro-organismsto biodegrade MWFs in bioreactor-based processes[25]. The most common extracted bacterialisolates are Pantoea agglomeraus, Citrobacter freundii,P. aeruginosa, Actinobacillus liginieresii [10].Van der Gast and colleagues have also carriedout a series of waste MWF treatment studies. In theirwork, the indigenous bacterial communities havebeen identified. Also comparisons of the overall performanceamong activated sludge from municipalsewage works, indigenous communities and bacterialconsortia have been made. They proved thatintroducing specific bacterial consortia was moreeffective. The technique of bacterial inoculation isnamed bioaugmentation, which is where additionalorganisms are added to enhance the treatment levelwhen the existing microorganisms are not degradingthe pollutant satisfactorily [24].In the CEC-L-33-T-82 is as the extracting solutionused 1,1,2-trichloro-1,1,2-trifluoroethane whichaffect the ozonosphere. Potential alternative carbontetrachloride is well-known human carcinogen.The main aims of this study were:‣ Evaluate the level of biodegradation of selectedmetalworking fluids standards and samplesfrom the plant by Zahn-Wellens test (OECD302B) for inherent biodegradability.‣ Evaluate potential adsorption after 3 hours ofcultivating and assessment applicability of thetest for measuring the biodegradability.‣ Evaluate potential of activated sludge from sewagetreatment plant to degrade the selectedMWFs.‣ Preliminary study to evaluate the ecotoxicityby Lemna minor.MATERIALS AND METHODS1. Preliminary biodegradability study – Zahn--Wellens test.Metalworking Fluids SourceIn experiments were used four types of metalworkingfluids standards and samples from theplant – Emulzin H, Ecocool and Blascocut BC 25that were obtained from ZVS Dubnica nad Váhom.In the test were used concentrations of cutting fluidsthat affect 1000–1400 mg/L of COD.Preparing Samples for COD Measuring5 ml of sample was filtered in frit S4. In leachatewas measuring the content of chemical oxygendemand. The measurements of chemical oxygendemand were realized in thermoreactor andspectrophotometer by fi. Merck.Source and Preparing of InoculumAs an inoculum was used fresh activated sludgefrom thesewage treatment plant Volkswagen inBratislava on the same day as the experiment started(or the day before) and leave in dark or diffuselight and cold place. Inoculum was washing twicewith tap water. The sludge was separated by settlement.The activity of the sludge was controlled bythe procedural control using a reference compound.As a reference substance was used ethylenglycol.In each test was used 0.5 g of dry matter/L in finalvolume. Volume of inoculum was evaluated afterdrying the special amount in the drying plant typeHERAEUS to the constant weight at 60 °C. Samplesof MWFs from the plant were contaminatedby microorganisms at the rate 10 5 –10 6 (contaminationby moulds and yeast were not achieved).Sample preparationIt was tested metalworking fluids samples preparedfrom concentrate diluted to required concentrationwith mineral medium prepared by [29] andsamples from the plant ZVS in Dubnica nad Váhomwith concentration in the range 0.5–5 Vol.% thatwere also diluted to the required concentration ofCOD in the test up to 1400 mg/L. Samples werecultivated in diffuse light at the temperature range20–25 °C. Mix of inoculum, mineral medium andtest or reference substance were aerated continuouslyby the membrane pump M401 and aerationpumps.Validity of the tests and measuring parametersThe test is considered valid if the control showsthe removal of the reference compound by at least70 % within 14d and if the removal of COD. Ifit is reached 80 % of degradation in the test substancebefore 28d, the test considers finished. If the