Tadeusz Miśkiewicz

Biodegradation of potato slops from a rural distillery by thermophilic aerobic bacteria

A study has been made of thermophilic aerobic biodegradation of the liquid fraction of potato slops (distillation residue) from a rural distillery. The COD of this fraction ranged from 49 to 104 g O2/l, the main contributions to the COD coming from organic acids, reducing substances, and glycerol. It was found that biodegradation could be divided into the following stages: organic acids were removed first, followed by reducing substances and glycerol. The extent of removal varied according to the process temperature. At 50 degrees C, acetic and malic acids were removed completely, but the amount of isobutyric acid increased. At 60 degrees C, organic acid removal ranged from 51.2% (isobutyric acid) to 99.6% (lactic acid). Removals of glycerol and reducing substances were 86.2% and 87.4%, respectively. COD reduction was also temperature dependent, the highest removal efficiency (76.7%) being achieved at 60 degrees C. Dissolved oxygen may have limited the biodegradation process, as indicated by the DOT-versus-time profile.

Effect of temperature on the efficiency of the thermo- and mesophilic aerobic batch biodegradation of high-strength distillery wastewater (potato stillage)

The objective of the study was to assess the effect of temperature on the extent of aerobic batch biodegradation of potato stillage with a mixed culture of bacteria of the genus Bacillus. The experiments were performed in a 5-l stirred-tank reactor at 20, 30, 35, 40, 45, 50, 55, 60, 63 and 65 degrees C with the pH of 7. Only at 65 degrees C, no reduction in chemical oxygen demand (COD) was found to occur. Over the temperature range of 20-63 degrees C, the removal efficiency was very high (with an extent of COD reduction following solids separation that varied between 77.57% and 89.14% after 125 h). The process ran at the fastest rate when the temperature ranged from 30 to 45 degrees C; after 43 h at the latest, COD removal amounted to 90% of the final removal efficiency value obtained for the process. At 20, 55, 60 and 63 degrees C, a 90% removal was attained after 80 h. Two criteria were proposed for the identification of the point in time when the process is to terminate. One of these consists in maximising the product of the extent of COD reduction and the extent of N-NH4 content reduction. The other criterion is a simplified one and involves the search for the minimal value of N-NH4 concentration.

Performance of an anaerobic bioreactor with biomass recycling, continuously removing COD and sulphate from industrial wastes.

A 30-l anaerobic bioreactor with biomass recycling was used to provide a continuous reduction in sulphate and a continuous COD removal from wastewater, which consisted of the effluent from an industrial pig fattening farm, enriched with technical FeSO(4) x 7H(2)O, a waste product from ferrous metallurgy. The concentrations of sulphate and COD in the wastewater amounted to 2.73 g l(-1) and 3.15 g l(-1), respectively. The HRT (hydraulic retention time) of 10-1.7d produced an extent of sulphate and COD reduction which totalled 98% and 88%, respectively. When the HRT was further shortened, the efficiency of reduction in sulphate and COD decreased. The maximum removal rate constants for both the pollutants, calculated by means of a modified Stover-Kincannon model, were 80.9 g COD l(-1)d(-1) and 41.8 g SO(4)(2-)l(-1)d(-1), the values of the saturation constants being 91.582 g COD l(-1)d(-1) and 42.398 g SO(4)(2-)l(-1)d(-1).

Thermo- and mesophilic aerobic batch biodegradation of high-strength distillery wastewater (potato stillage) - Utilisation of main carbon sources

The aim of the study was to ascertain the extent to which temperature influences the utilisation of main carbon sources (reducing substances determined before and after hydrolysis, glycerol and organic acids) by a mixed culture of thermo- and mesophilic bacteria of the genus Bacillus in the course of aerobic batch biodegradation of potato stillage, a high-strength distillery effluent (COD=51.88 g O(2)/l). The experiments were performed at 20, 30, 35, 40, 45, 50, 55, 60 and 63 degrees C, at pH 7, in a 5l working volume stirred-tank bioreactor (Biostat B, B. Braun Biotech International) with a stirrer speed of 550 rpm and aeration at 1.6 vvm. Particular consideration was given to the following issues: (1) the sequence in which the main carbon sources in the stillage were assimilated and (2) the extent of their assimilation achieved under these conditions.

Betaine removal during thermo- and mesophilic aerobic batch biodegradation of beet molasses vinasse: Influence of temperature and pH on the progress and efficiency of the process

The key issue in achieving a high extent of biodegradation of beet molasses vinasse is to establish the conditions for the assimilation of betaine, which is the main pollutant in this high-strength industrial effluent. In the present study, aerobic batch biodegradation was conducted over the temperature range of 27-63°C (step 9°C), at a pH of 6.5 and 8.0, using a mixed culture of bacteria of the genus Bacillus. Betaine was assimilated at 27-54°C and the pH of 8.0, as well as at 27-45°C and the pH of 6.5. The processes where betaine was assimilated produced a high BOD(5) removal, which exceeded 99.40% over the temperature range of 27-45°C at the pH of 8.0, as well as at 27°C and the pH of 6.5. Maximal COD removal (88.73%) was attained at 36°C and the pH of 6.5. The results indicate that the process can be applied on an industrial scale as the first step in the treatment of beet molasses vinasse.

Upgrading the efficiency of dissimilatory sulfate reduction by Desulfovibrio desulfuricans via adjustment of the COD/SO4 ratio

The potential for upgrading the microbiological reduction of sulfates and for decreasing the organic pollution levels in industrial waste-water by the adjustment of the COD/SO4 ratio was investigated. The experiments involved waste-water samples coming from industrial pig farming, bakers yeast production and organic dye manufacture. The results show that in the presence of Desulfovibrio desulfuricans both the objectives can be achieved by abating the disproportion between the content of sulfates and that of organic substances.

Efficiency of aerobic biodegradation of beet molasses vinasse under non-controlled pH: conditions for betaine removal / Efektywność tlenowej biodegradacji buraczanego wywaru melasowego przy nieregulowanym pH podłoża: określenie warunków usunięcia betainy

Abstract The aim of the study was to establish such conditions that would provide high-efficiency aerobic biodegradation of beet molasses vinasse with a mixed culture of thermo- and mesophilic bacteria of the genus Bacillus in batch processes without controlling the pH of the medium. Particular consideration was given to the betaine removal (the main pollutant of vinasse), which accounted for as much as 37.6% of total organic carbon. Biodegradation was performed in a stirred tank reactor at 27-63°C with initial pH (pH0) of 6.5 and 8.0. Efficiency of biodegradation was expressed in terms of reduction in SCODsum, which is a sum of SCOD (soluble chemical oxygen demand, i.e. COD determined after suspended solids separation) and theoretical COD of betaine. The values achieved at 27 and 36°C with pH0 = 8.0 exceeded 77.7%, whereas those obtained at 36 and 45°C with pH0 = 6.5 were higher than 83.6%. The high biodegradation efficiency obtained in the four processes is attributable to the betaine removal by the bacterial strains used in the study. Maximal extent of reduction in SCODsum (85.41%), BOD5 (97.91%) and TOC (86.32%), and also the fastest rate of biodegradation (1.17 g O2/l∙h) was achieved at 36°C and pH0 = 8.0 Celem pracy było określenie warunków zapewniających wysoką efektywność tlenowej biodegradacji buraczanego wywaru melasowego za pomocą mieszanej kultury termo- i mezofilnych bakterii z rodzaju Bacillus w procesach okresowych prowadzonych bez regulacji pH podłoża. Główną uwagę poświęcono usunięciu betainy (głównego zanieczyszczenia buraczanego wywaru melasowego). Stanowiła ona aż 37,6% zawartości ogólnego węgla organicznego w biodegradowanym wywarze. Procesy biodegra dacji prowadzono w 5-litrowym bioreaktorze z układem mieszania w temperaturze 27-63°C, co 9°C, dla pH początkowego (pH0) równego 6,5 i 8,0. Wysoką efektywność biodegradacji wyrażoną poprzez redukcję SChZTcałk (suma SChZT (ChZT oznaczane po oddzieleniu części stałych) i teoretycznego ChZT betainy) uzyskano w procesach prowadzonych w temperaturze 27 i 36°C dla pH0 = 8,0 (redukcja ponad 77,7%) oraz 36 i 45°C dla pH0 = 6,5 (redukcja ponad 83,6%). Przyczyną wysokiej efektywności biodegradacji w wymienionych czterech procesach było usunięcie przez bakterie betainy. Maksymalny stopień redukcji SChZTcałk (85,41%), BZT5 (97,91%) i OWO (86,32%), jak również największą szybkość biodegradacji (1,17 g O2/l∙h) uzyskano w eksperymencie prowadzonym w temperaturze 36°C dla pH0 = 8,0.