Irena Wojnowska-Baryła

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.

Structure of nitrogen-converting communities induced by hydraulic retention time and COD/N ratio in constantly aerated granular sludge reactors treating digester supernatant.

This study investigated how hydraulic retention time (HRT) and COD/N ratio affect nitrogen-converting consortia in constantly aerated granules treating high-ammonium digester supernatant. Three HRTs (10, 13, 19 h) were tested at COD/N ratios of 4.5 and 2.3. Denaturing gradient gel electrophoresis and relative real-time PCR were used to characterize the microbial communities. When changes in HRT and COD/N increased nitrogen loading, the ratio of the relative abundance of aerobic to anaerobic ammonium-oxidizers decreased. The COD/N ratio determined the species composition of the denitrifiers; however, Thiobacillus denitrificans, Pseudomonas denitrificans and Azoarcus sp. showed a high tolerance to the environmental conditions and occurred in the granules from all reactors. Denitrifier genera that support granule formation were identified, such as Pseudomonas, Shinella, and Flavobacterium. In aerated granules, nirK-possessing bacteria were more diverse than nirS-possessing bacteria. At a low COD/N ratio, N2O-reducer diversity increased because of the presence of bacteria known as aerobic denitrifiers.

Treatment of high-ammonium anaerobic digester supernatant by aerobic granular sludge and ultrafiltration processes.

Anaerobic sludge digester supernatant characterized by 569 mg TKN L(-1), high color and a COD/N ratio of 1.4 was treated in granular sequencing batch reactors (GSBRs) followed by post-denitrification (P-D) and ultrafiltration (UF) steps. The use of granular sludge allowed for the oxidation of ammonium in anaerobic digester supernatant at all investigated GSBR cycle lengths of 6, 8 and 12 h. The highest ammonium removal rate (15 mg N g(-1) VSS h(-1)) with removal efficiency of 99% was noted at 8 h. Since the GSBR effluent was characterized by a high concentration of nitrites, slowly-degradable substances and biomass, additional purification steps were applied. In P-D stage, the microbial activity of granular biomass in the GSBR effluent was implemented. The P-D was supported by external carbon source addition and the most advantageous variant comprised dosing of half of the theoretical acetate dose for nitrite reduction in the 3-h intervals. The use of the system consisting of the GSBR with 8 h, an optimal P-D variant and a UF for the treatment of anaerobic digester supernatant allowed for the 99%, 71% and 97% reductions of TKN, COD and color, respectively.

Nitrogen removal from wastewater with a low COD/N ratio at a low oxygen concentration

The goal of the study was to determine the effectiveness of nitrification and denitrification and the kinetics of ammonia removal from a mixture of wastewater and anaerobic sludge digester supernatant in an SBR at limited oxygen concentration. In addition, the COD removal efficiency and sludge production were assessed. In the SBR cycle alternating aerobic and anaerobic phases occurred; in the aeration phase the dissolved oxygen (DO) concentration was below 0.7 mg O(2)/L. The low DO concentration did not inhibit ammonia oxidation-nitrification and the efficiency was ca. 96-98%. However, a relatively high COD concentration in the effluent was detected. The values of K(m) and V(max), calculated from the Michaelis-Menten equation, were 43 mg N-NH(4)/L and 15.64 mg N-NH(4)/L h, respectively. Activated sludge production was almost stable (0.62-0.66 g MLVSS/g COD). A high net biomass production resulted from a low specific biomass decay rate of 0.0015 d(-1).

Effectiveness of leachate disposal by the young willow sprouts Salix amygdalina

The lysimeter experiment was conducted at the laboratory scale. Different water and leachate dilutions (0%, 25%, 50%, 100% of leachate) were supplied to the lysimeters to achieve the variation in pollutants concentration. The measure of leachate disposal effectiveness was the amount of evaporated leachate solution in evapotranspiration and transpiration. Analysis of evaporation dynamics and the impact of the plants on the leachate disposal effectiveness were determined. Correlation between biomass increase, transpiration and leachate concentration was observed. The highest evapotranspiration was obtained in the lysimeter with leachate concentration 25% and was on the level of 2.3 mm/day and for transpiration, 2.21 mm/day. The lowest values of evapotranspiration (0.55 mm/day) and transpiration (0.39 mm/day) were observed in the lysimeters supplied only by concentrated leachate. The highest leachate treatment efficiency 0.78 mm leachate/day was achieved in lysimeter K3-50% leachate concentration. There was an increase in transpiration participation in evapotranspiration in time. In the lysimeters supplied by the solutions with leachate concentrations, 25% and 50% transpiration participation in evapotranspiration ranged from 80% to 90%, in case of concentrated leachate from 60% to 70%. Evapotranspiration in all lysimeters was 3, 5-14 times higher than evaporation. It seems to be the result of plant impact on evaporation and confirms the possibility of this method being used for leachate treatment. Willows in lysimeter (K3-50% of leachate) had the most effective physiological fit to landfill leachate treatment.

The Application of Molecular Techniques to the Study of Wastewater Treatment Systems

Wastewater treatment systems tend to be engineered to select for a few functional microbial groups that may be organized in various spatial structures such as activated sludge flocs, biofilm or granules and represented by single coherent phylogenic groups such as ammonia-oxidizing bacteria (AOB) and polyphosphate-accumulating organisms (PAO). In order to monitor and control engineered microbial structure in wastewater treatment systems, it is necessary to understand the relationships between the microbial community structure and the process performance. This review focuses on bacterial communities in wastewater treatment processes, the quantity of microorganisms and structure of microbial consortia in wastewater treatment bioreactors. The review shows that the application of molecular techniques in studies of engineered environmental systems has increased our insight into the vast diversity and interaction of microorganisms present in wastewater treatment systems.

The treatment of anaerobic digester supernatant by combined partial ammonium oxidation and denitrification

Abstract Although the most common method of municipal reject water management is treating in the main flow of a wastewater treatment plant, an alternative method is purifying it separately in a side-stream. This helps to reduce the load of nitrogen and carbon entering the sewage treatment system. This paper reports the results of the application of the SBR for the treatment of anaerobic sludge digester supernatant. At a reduced dissolved oxygen (DO) concentration of 0.7 mg O2/l in the aeration phase, application of mixing phases and pH regulation at the beginning of the SBR cycle (pH 8) allowed to obtain a suitable Anammox influent (50/50 ammonium:nitrite). Applying low oxygen concentrations and a one-hour long mixing phase enabled heterotrophic denitrification in the reactor. The partial use of organic compounds in this process resulted in a COD/N ratio in the effluent of ca. 1, which is favourable for the Anammox influent.

Nitrogen removal from wastewater and bacterial diversity in activated sludge at different COD/N ratios and dissolved oxygen concentrations

The impact of the organic carbon to nitrogen ratio (chemical oxygen demand (COD)/N) in wastewater and dissolved oxygen (DO) concentration on carbon and nitrogen removal efficiency, and total bacteria and ammonia-oxidizing bacteria (AOB) communities in activated sludge in constantly aerated sequencing batch reactors (SBRs) was determined. At DO of 0.5 and 1.5 mg O2/L during the aeration phase, the efficiency of ammonia oxidation exceeded 90%, with nitrates as the main product. Nitrification and denitrification achieved under the same operating conditions suggested the simultaneous course of these processes. The most effective nitrogen elimination (above 50%) was obtained at the COD/N ratio of 6.8 and DO of 0.5 mg O2/L. Total bacterial diversity was similar in all experimental series, however, for both COD/N ratios of 6.8 and 0.7, higher values were observed at DO of 0.5 mg O2/L. The diversity and abundance of AOB were higher in the reactors with the COD/N ratio of 0.7 in comparison with the reactors with the COD/N of 6.8. For both COD/N ratios applied, the AOB population was not affected by oxygen concentration. Amplicons with sequences indicating membership of the genus Nitrosospira were the determinants of variable technological conditions.

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...

The controlling of landfill leachate evapotranspiration from soil-plant systems with willow : Salix amygdalina L

The use of willows (Salix amygdalina L) to manage landfill leachate disposal is an effective and cost-effective method due to the high transpiration ability of the willow plants. A 2-year lysimetric experiment was performed to determine an optimum leachate hydraulic loading rate to achieve high evapotranspiration but exert no harmful influence on the plants. The evapotranspiration rate of a soil–plant system planted with the willow was 1.28–5.12-fold higher than the rate measured on a soil surface lacking vegetation, suggesting that soil– willow systems with high volatilization rates are a viable landfill leachate treatment method. Of the soil–willow systems, the one with willow growing on sand amended with sewage sludge soil at an hydraulic loading rate of 1 mm day-1 performed best, with evapotranspiration ranging from 2.25 to 3.02 mm day-1 and a biomass yield of 8.0–9.85 Mg dry matter ha-1. The organic fraction of the soil increased as much as 2.5% of dry matter, due to the sewage sludge input, which exerted a positive effect on the biomass yield as well as on transpiration and evaporation. It was observed that the plants in the sand-and-sewage sludge soil systems displayed higher resistance to toxic effects from the applied landfill leachate relative to plants in the sand–soil systems.