Ewa Klimiuk

Theoretical and observed biogas production from plant biomass of different fibre contents

The methane productivity of silage of four crop species -Zeamays L., Sorghumsaccharatum, Miscanthusxgiganteus and Miscanthussacchariflorus - was investigated. The experiments revealed that at a hydraulic retention time of 60days the volumetric methane yields from the Z.mays L. or S.saccharatum silages were higher than those from the Miscanthusxgiganteus or M.sacchariflorus silages because of the higher crude fibre content in Miscanthus spp. However, at comparable lignin concentrations in the feedstock, methane productivity for M.sacchariflorus (0.19+/-0.08L/g volatile solids) was twice that of Miscanthusxgiganteus (0.10+/-0.03L/g volatile solids). The efficiency of cellulose conversion varied from 83.6% (S. saccharatum) to 52.1% (Miscanthusxgiganteus), and hemicellulose from 88.9% (Z. mays L.) to 59.7% (Miscanthusxgiganteus). Conversion of cellulose and hemicellulose depended on the ratio of these polysaccharides to the lignin concentration of the feedstock.

Metal (Cu, Cd and Zn) removal and stabilization during multiple soil washing by saponin

The influence of multiple saponin washing on copper, cadmium and zinc removal and stability in three types of soils (loamy sand, loam, silty clay) was investigated. Distribution of metals and their mobility measured as the ratio of exchangeable form to the sum of all fractions in soils was differential. After single washing the highest efficiency of metal removal was obtained in loamy sand (82-90%) and loam (67-88%), whereas the lowest in silty clay (39-62%). In loamy sand and loam metals had higher mobility factors (44-61% Cu, 60-76% Cd, and 68-84% Zn) compared to silty clay (9% Cu, 28% Cd and 36% Zn). Triplicate washing led to increase both efficiency of metal removal and percentage content of their stable forms. In consequence, fractional patterns for metals before and after treatment changed visibly as a result of their redistribution. Based on the redistribution index, the most stable metal (mainly in residual and organic fractions) after triplicate washing was Cu in loamy sand and loam. For silty clay contaminated with Cd, effective metal removal and its stabilization required a higher number of washings.

Molecular detection and diversity of medium-chain-length polyhydroxyalkanoates-producing bacteria enriched from activated sludge

Aims:  Knowledge of the species composition of complex bacterial communities is still very limited. The main objectives of this study were to identify medium‐chain‐length polyhydroxyalkanoates (mcl‐PHAs)‐producing bacteria from activated sludge fed with methanol as well as to characterize their PHA operon.

Organic matter transformations and kinetics during sewage sludge composting in a two-stage system.

The use of different proportions of rape straw and grass as amendments in the composting of dewatered sewage sludge from a municipal wastewater treatment plant was tested in a two-stage system (first stage, an aerated bioreactor and second stage, a periodically turned windrow). The composition of feedstock affected the temperature and organic matter degradation in the bioreactor and the formation of humic substances, especially humic acids (HA), during compost maturation in the windrow. The total HA content (the sum of labile and stable HA) increased according to first-order kinetics, whereas labile HA content was constant and did not exceed 12% of total HA. ΔlogK of 1.0-1.1 indicated that HA was of R-type, indicating a low degree of humification. Temperature during composting was the main factor affecting polymerization of fulvic acids to HA and confirmed the value of the degree of polymerization, which increased only when thermophilic conditions were obtained.

Semi-continuous anaerobic digestion of different silage crops: VFAs formation, methane yield from fiber and non-fiber components and digestate composition

This study presents the results of long-term semi-continuous experiments on anaerobic digestion at an HRT of 45d with ten silages: 2 annual and 4 perennial crops, and 4 mixtures of annual with perennial crops. The composition of substrates and digestates was determined with Van Soests fractionation method. Removal of non-fiber materials ranged from 49.4% (Miscanthus sacchariflorus) to 89.3% (Zea mays alone and mixed with M. sacchariflorus), that of fiber materials like lignin ranged from 0.005% (Z. mays alone and mixed with grasses at VS ratio of 90:10%) to 46.5% (Sida hermaphrodita). The lowest stability of anaerobic digestion, as confirmed by normalized data concentrations of volatile fatty acids, was reported for both miscanthuses and sugar sorghum. The methane yield coefficients for non-fiber and fiber materials were 0.3666 and 0.2556L/g, respectively. All digestate residues had high fertilizing value, especially those from mixtures of crops.

Molecular insight into activated sludge producing polyhydroxyalkanoates under aerobic–anaerobic conditions

One of the options enabling more economic production of polyhydroxyalkanoates compared to pure cultures is the application of mixed cultures. The use of a microbial community in a sequencing batch reactor has a few advantages: a simple process control, no necessity for sterile processing, and possibilities of using cheap substrates as a source of carbon. Nevertheless, while cultivation methods to achieve high PHAs biomass concentration and high productivity in wild and recombinant strains are defined, knowledge about the cultivation strategy for PHAs production by mixed culture and species composition of bacterial communities is still very limited. The main object of this study was to characterize on the molecular level the composition and activity of PHAs producing microorganism in activated sludge cultivated under oxygen limitation conditions. PHAs producers were detected using a PCR technique and the created PHA synthase gene library was analyzed by DNA sequencing. The obtained results indicate that PHAs-producers belonged to Pseudomonas sp., and possessed genes coding for mcl-PHA synthase. The kinetics of mcl-PHA synthase expression was relatively estimated using real-time PCR technology at several timepoints. Performed quantitative and qualitative analysis of total bacterial activity showed that there were differences in total activity during the process but differential expression of various groups of microorganisms examined by using DGGE was not observed.

The influence of operational conditions in sequencing batch reactors on removal of nitrogen and organics from municipal landfill leachate

The removal of nitrogen and organics from municipal landfill leachate in sequencing batch reactors (SBR) was investigated in the present study. The influence of hydraulic retention time (HRT), sludge age, manner of leachate dosage (short filling period of SBR and filling during the reaction period), and operational conditions with and without a mixing phase in the SBR cycle was explored. Four series were performed. In each series, the HRT used in the four SBRs was 12, 6, 3 and 2 days, respectively. Series 1 and 2 were characterized by a short leachate filling period, whereas series 3 and 4 were characterized by filling during the 4 h duration of the reaction in the SBR cycle. In series 1–3 SBR reactors worked with mixing and aeration phases, whereas in series 4 they worked only with an aeration phase. The effectiveness of the removal of organics increased with the extension of the HRT of leachate, particularly under operational conditions with the mixing and aeration phases in the SBR cycle. At 12 days HRT, the SBRs with the mixing and aeration phases in the cycle (series 1–3) showed better results than those with only an aeration phase (series 4). However, at 2 days HRT the operational conditions in SBR reactors with leachate filling over the reaction period (series 3 and 4) were more suitable. The highest efficiency of ammonium removal was obtained in series 1 with a short leachate filling period. In this series, at an HRT of 3– 12 days, the ammonium concentration in the effluent did not exceed 1 mg NNH4 L–1. Nitrogen removal proceeded mainly in the aeration phase as a result of ammonium losses and, to a lesser extent, dissimilative nitrate reduction over the mixing phase. The highest percentage of nitrogen removal as a result of ammonium losses was observed in series with a short filling period and long sludge age (series 1) and also in series without a mixing phase and filling over the aeration phase (series

ADM1-based modeling of anaerobic codigestion of maize silage and cattle manure – a feedstock characterisation for model implementation (part I) / Modelowanie kofermentacji kiszonki kukurydzy i obornika bydlęcego za pomocą ADM1 – charakterystyka wsadu surowcowego (część I)

Abstract This paper presents the results of fractionation of particulate and soluble organic matter in a mixture of maize silage and cattle manure (49:51% volatile solids) that was used as a feedstock for anaerobic digestion. The extended Weender’s analysis was adapted to measure raw protein, raw lipids, fraction of carbohydrates (including starch, cellulose, hemicelluloses) and lignin. The content of individual fractions in composite, Xc (as kg COD kg-1 COD) was: 0.111 proteins, 0.048 lipids, 0.500 carbohydrates and 0.341 inerts. The biodegradability of Xc was 68%. Based on material balance, the carbon concentration in Xc was 0.0326 kmol C kg-1 COD, whereas nitrogen concentration 0.0018 kmol N kg-1 COD. The estimated pH of the feedstock based on acid-base equilibrium corresponded to the actual value (pH 7.14). Streszczenie W pracy przedstawiono wyniki stężenia substancji chemicznych rozpuszczonych i nierozpuszczonych w mieszaninie kiszonki kukurydzy zwyczajnej i obornika bydlęcego (49:51% suchej masy organicznej), który wykorzystano jako substrat do wytwarzania biogazu. Do frakcjonowania nierozpuszczalnych związków organicznych, stanowiących kompozyt (Xc), wykorzystano metodę Weender’a. Udział poszczególnych frakcji (jako ChZT) w kompozycie wyniósł: białka - 0,111, tłuszcze - 0,048, węglowodany - 0,500 oraz związki inertne - 0,341. Stężenie związków biodegradowalnych w kompozycie wyniosło 68%. Na podstawie bilansu materiałowego węgla i azotu obliczono, że stężenie węgla w kompozycie wynosi 0,0326 kmol C kg-1 ChZT, zaś azotu 0,0018 kmol N kg-1 ChZT. Odczyn (pH) wsadu surowcowego wyznaczony z równowagi kwasowo-zasadowej odpowiadał rzeczywistemu, tj. 7,14.

ADM1-based modeling of anaerobic codigestion of maize silage and cattle manure – calibration of parameters and model verification (part II) / Modelowanie kofermentacji kiszonki kukurydzy i obornika bydlęcego za pomocą ADM1 – kalibracja i weryfikacja modelu (część II)

Abstract The aim of this study was to implement ADM1xp model to simulate behavior of anaerobic co-digestion of maize silage and cattle manure. The accuracy of ADM1xp has been assessed against experimental data of anaerobic digestion, performed at OLR = 2.1 gVS dm-3·d-1 and HRT = 45d. Due to the high number of parameters in ADM1xp, it was necessary to develop a customized procedure limiting the range of parameters to be estimated. The best fitting of experimental to simulated data was obtained after verification of 9 among 105 stoichiometric and kinetic parameters. The values of objective function (Jc) ranged between 0.003 (for valerate) and 211 (for biogas production). Streszczenie Celem pracy było wykorzystanie modelu ADM1xp do symulacji procesu kofermentacji kiszonki kukurydzy i obornika bydlęcego. Przydatność modelu oceniano wykorzystując dane z eksperymentu w skali laboratoryjnej. Badania prowadzono przy obciążeniu komory ładunkiem organicznym OLR = 2,1 gVS dm-3·d-1 oraz hydraulicznym czasie zatrzymania wsadu w fermentorze, HRT = 45d. Z powodu dużej liczby parametrów w modelu ADM1xp, zastosowano procedurę, która umożliwia zmniejszenie liczby weryfi kowanych parametrów podczas kalibracji. Najlepsze dopasowanie danych eksperymentalnych do modelowych uzyskano po weryfikacji 9 spośród 105 stechiometrycznych i kinetycznych parametrów. Wartości współczynnika dopasowania (Jc) zmieniały się w zakresie od 0,003 (kwas walerianowy) do 211 (produkcja biogazu).

Optimization of anaerobic digestion of a mixture of Zea mays and Miscanthus sacchariflorus silages with various pig manure dosages.

Digestion of crop silage (Zea mays L. and Miscanthus sacchariflorus) with 0%, 7.5%, 12.5% and 25% pig manure as co-substrate was performed in continuous stirred-tank reactors, for a constant hydraulic retention time of 45 d and organic load rate of 2.1 g L(-1)d(-1). A matrix of correlations between biogas/methane production and parameters of anaerobic digestion was created in order to estimate process stability. The values of the correlation coefficients indicated that the most stable anaerobic digestion was achieved using 7.5% and 12.5% pig manure. In contrast, the positive correlation between ammonium and volatile fatty acids (r=0.8698, p<0.001) at 25% pig manure showed process instability. Compared to crop silage alone, pig manure favored the production of biogas and methane; the highest production rates were obtained with 12.5% pig manure.