Katarzyna Bułkowska

Feasibility of using humic substances from compost to remove heavy metals (Cd, Cu, Ni, Pb, Zn) from contaminated soil aged for different periods of time

There is a need for inexpensive, readily-available and environmentally-friendly soil washing agents to remediate polluted soils. Thus, batch washing experiments were performed to evaluate the feasibility of using a solution of humic substances (HS) extracted from compost as a washing agent for simultaneous removal of Cu, Cd, Zn, Pb and Ni from artificially contaminated soils aged for 1 month, 12 months and 24 months. The efficiency of metal removal in single and multiple washings and kinetic constants (equilibrium metal concentration qe and rate constant k from the second-order kinetic equation) were determined. On average, triple washing removed twice as much metal as that removed with a single washing. At pH 7 and a HS concentration of 2.2 g C L(-1), metal removal from all soils decreased in this order: Cd (79.1-82.6%) > Cu (51.5-71.8%) > Pb (44.8-47.6%) > Ni (35.4-46.1%) > Zn (27.9-35.8%). However, based on qe (mg kg(-1)), metal removal was in this order: Pb > Zn ≈ Cu > Ni > Cd. This difference was due to different concentrations of metals, which is typical for multi-metal contaminated soils. Regardless of washing mode, removal of Cd and Pb was not affected by soil age, whereas removal of Cu, Ni and Zn was higher in soils that had been aged for a shorter time. These results indicate that HS are suitable for remediating soil contaminated with multiple heavy metals in extremely high concentrations.

Humic substances from sewage sludge compost as washing agent effectively remove Cu and Cd from soil

Although commercially available biosurfactants are environmentally friendly and effectively remove heavy metals from soil, they are costly. Therefore, this study investigated whether inexpensive humic substances (HS) from sewage sludge compost could effectively remove copper (Cu) and cadmium (Cd) from highly contaminated sandy clay loam (S1) and clay (S2). The optimum HS concentration and pH were determined, as well process kinetics. Under optimum conditions, a single washing removed 80.7% of Cu and 69.1% of Cd from S1, and 53.2% and 36.5%, respectively, from S2. Triple washing increased removal from S1 to almost 100% for both metals, and to 83.2% of Cu and 88.9% of Cd from S2. Triple washing lowered the potential ecological risk (Er(i)) of the soils, especially the risk from Cd. HS substances show potential for treating soils highly contaminated with heavy metals, and HS from other sources should be tested with these and other contaminants.

Removal of bisphenol A (BPA) in a nitrifying system with immobilized biomass.

The potential for bisphenol A (BPA) removal by mixed consortia of immobilized microorganisms with high nitrification activity was investigated with BPA concentrations in the influent from 2.5 to 10.0 mg/L. The presence of BPA limited ammonium oxidation; nitrification efficiency decreased from 91.2±1.3% in the control series to 47.4±9.4% when BPA concentration in wastewater was the highest. The efficiency of BPA removal rose from 87.1±5.5% to 92.9±2.9% with increased BPA concentration in the influent. Measurement of oxygen uptake rates by biomass exposed to BPA showed that BPA was mainly removed by heterotrophic bacteria. A strong negative correlation between the BPA removal efficiency and nitrification efficiency indicated the limited contribution of ammonia-oxidizing bacteria (AOB) to BPA biodegradation. Exposure of biomass to BPA changed the quantity and diversity of AOB in the biomass as shown by real-time PCR and denaturing gradient gel electrophoresis.

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.

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).

Removal of phenanthrene and 4-phenylphenanthrene from wastewater in an integrated technological system

Abstract An integrated system, consisting of a bioreactor with a nitrifying immobilized biomass and a membrane reactor, was tested for its ability to remove two polycyclic aromatic hydrocarbons (PAHs)—phenanthrene (PHE) and 4-phenylphenanthrene (4-PPHE)—from wastewater. An almost complete removal of the selected PAHs was observed under the operational conditions applied (0.6 mg PHE/l or a mixture of 0.6 mg PHE/l and 0.6 mg 4-PPHE/l in the influent, retention time in an aerated bioreactor of 1.5 h, transmembrane pressure of the ultrafiltration membrane 1 bar). Permeate concentration was below 2 μg PAH/l. The introduction of the PHE and an increase in organic loading (Q V) from 4.9 kg chemical oxygen demand (COD)/(m3 day) to 6.7 kg COD/(m3 day) resulted in a decline in nitrification efficiency from 87.6 to 53.0%. A further increase in Q V to 8.4 kg COD/(m3 day) by supplying an additional 4-PPHE induced neither ammonia oxidation nor PAH removal. The diversity of ammonia-oxidizing bacteria was not affected by...

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.

Effect of different nitrogen fertilizer treatments on the conversion of Miscanthus × giganteus to ethanol

Miscanthus×giganteus is a perennial rhizomatous grass which is used as a biofuel crop. Due to its high yields, low production costs, resistance to low temperatures, low soil requirements and, above all, high cellulose content, miscanthus can be a useful resource for ethanol production. The aim of this study was to determine the effect of two fertilization regimes (sewage sludge/mineral NPK) during miscanthus cultivation on the chemical composition of biomass, the content of major lignocellulosic factions and the effectiveness of miscanthus conversion to bioethanol. The results indicate that fertilization treatments influenced biomass yield and the content of major lignocellulosic fractions. Bioethanol production was higher when hydrolysis and fermentation processes were conducted separately than when saccharification and fermentation were conducted simultaneously. Ethanol production increased by 30% and 40% in response to sewage sludge and NPK (equivalent nitrogen content=160kgN/ha) fertilization, respectively, in comparison with unfertilized crops.

PRODUCTION OF BIOGAS USING MAIZE SILAGE SUPPLEMENTED WITH RESIDUAL GLYCERINE FROM BIODIESEL MANUFACTURING

Abstract The aim of this study was to investigate the influence of residual glycerine (5 and 10% w/w) from the biodiesel industry, used as a co-substrate, on biogas production from maize silage. The experiments were conducted in a laboratory-scale, single-stage anaerobic digester at 39ºC and hydraulic retention time (HRT) of 60 d. Addition of 5% residual glycerine caused organic load rate (OLR) to increase to 1.82 compared with 1.31 g organic dry matter (ODM) L-1d-1 for maize silage alone. The specific biogas production rate and biogas yield were 1.34 L L-1d-1 and 0.71 L g ODM-1 respectively, i.e. 86% and 30% higher than for maize alone. Increasing the residual glycerine content to 10% increased OLR (2.01 g ODM L-1d-1), but clearly decreased the specific biogas production rate and biogas yield to 0.50 L L-1d-1 and 0.13 L g ODM-1 respectively. This suggested that 10% glycerine content inhibited methanogenic bacteria and organics conversion into biogas. As a result, there was accumulation of propionic and valeric acids throughout the experiment.