The inhibition of undesirable nitrite oxidizing bacteria (NOB) and desirable ammonium oxidizing bacteria (AOB) by free ammonia (FA) and free nitrous acid (FNA) in partial nitritation (PN) is crucially affected by the biomass growth mode (suspended sludge, biofilm, encapsulation). But, the limitations of these modes towards less concentrated reject waters (≤600 mg-N L-1) are unclear. Therefore, this work compares the start-up and stability of three PN sequencing batch reactors (SBRs) with biomass grown in one of the three modes: suspended sludge, biofilm and biomass encapsulated in polyvinyl alcohol (PVA) pellets. The SBRs were operated at 15°C with influent total ammonium nitrogen (TAN) concentrations of 75-600 mg-TAN L-1. PN start-up was twice as fast in the biofilm and encapsulated biomass SBRs than in the suspended sludge SBR. After start-up, PN in the biofilm and suspended sludge SBRs was stable at 150-600 mg-TAN L-1. But, at 75 mg-TAN L-1, full nitrification gradually developed. In the encapsulated biomass SBR, full nitrification occurred even at 600 mg-TAN L-1, showing that NOB in this set-up can adapt even to 4.3 mg-FA L-1 and 0.27 mg-FNA L-1. Thus, PN in the biofilm was best for the treatment of an influent containing 150-600 mg-TAN L-1.
- MeSH
- amoniové sloučeniny * MeSH
- Bacteria MeSH
- biomasa MeSH
- bioreaktory MeSH
- dusitany * MeSH
- odpadní vody MeSH
- oxidace-redukce MeSH
- Publikační typ
- časopisecké články MeSH
Postaeration, where digested sludge is introduced into aerobic conditions, is a technology that could improve the quality of sludge and sludge liquor in many ways. Although it is a fairly simple process, only few data about the effect of postaeration have been published. In this study, batch experiments have been performed first, indicating that postaeration affects the total ammonia nitrogen (TAN) and sludge dewaterability. In the removal of TAN, both stripping and biological oxidation can play an important role depending on specific condition. Then the postaeration was investigated in a semicontinuous batch reactor. In addition, the effect of postaeration on the concentration of selected micropollutants such as pharmaceuticals, EOX and AOX was studied. The hydraulic retention time (HRT) of 8, 6, 4 and 2 days and different aeration intensities were tested. The TAN removal efficiency achieved was about 40-60%, sludge dewaterability expressed by sludge cake total solids (TS) concentration after dewatering improved relatively by 5-30%. In addition, TS degradation is also taking place and therefore the reduction of the amount of final sludge to be disposed could be even higher. The biggest changes in observed parameters were recorded at the longest HRT.
- MeSH
- amoniak MeSH
- bioreaktory MeSH
- dusík MeSH
- odpad tekutý - odstraňování * MeSH
- odpadní vody * MeSH
- Publikační typ
- časopisecké články MeSH
The adaptation of Anammox (ANaerobic AMMonium OXidation) to low temperatures (10-15°C) is crucial for sustaining energy-efficient nitrogen removal from the mainstream of municipal wastewater. But, current adaptation methods take months or even years. To speed up the adaption of Anammox to low temperatures, this study describes a new approach: exposing Anammox microorganisms to an abrupt temporary reduction of temperature, i.e., cold shock. Anammox biomass in a moving bed biofilm reactor was subjected to three consecutive cold shocks (reduction from 24 ± 2 to 5.0 ± 0.2°C), each taking eight hours. Before the cold shocks, Anammox activity determined in ex situ tests using the temperature range of 12.5-19.5°C was 0.005-0.015 kg-N kg-VSS-1 day-1 . Cold shocks increased the activity of Anammox at 10°C to 0.054 kg-N kg-VSS-1 day-1 after the third shock, which is similar to the highest activities obtained for cold-enriched or adapted Anammox reported in the literature (0.080 kg-N kg-VSS-1 day-1 ). Fluorescence in situ hybridization analysis showed that Ca. Brocadia fulgida was the dominant species. Thus, cold shocks are an intriguing new strategy for the adaptation of Anammox to low temperature. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 34:277-281, 2018.
- MeSH
- amoniové sloučeniny chemie MeSH
- anaerobióza genetika MeSH
- Bacteria genetika růst a vývoj metabolismus MeSH
- biofilmy růst a vývoj MeSH
- bioreaktory MeSH
- čištění vody metody MeSH
- denitrifikace genetika MeSH
- dusík metabolismus MeSH
- hybridizace in situ fluorescenční MeSH
- nízká teplota MeSH
- odpad tekutý - odstraňování metody MeSH
- oxidace-redukce MeSH
- reakce na chladový šok genetika MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Hydrogen sulfide in biogas is common problem during anaerobic treatment of wastewater with high sulfate concentration (breweries, distilleries, etc.) and needs to be removed before biogas utilization. Physico-chemical desulfurization methods are energetically demanding and expensive compare to biochemical methods. Microaeration, i.e. dosing of small amount of air, is suitable and cost effective biochemical method of sulfide oxidation to elemental sulfur. It has been widely used in biogas plants, but its application in anaerobic reactors for wastewater treatment has been rarely studied or tested. The lack of full-scale experience with microaeration in wastewater treatment plants has been overcome by evaluating the results of seven microaerobic digesters in central Europe. The desulfurization efficiency has been more than 90% in most of the cases. Moreover, microaeration improved the degradability of COD and volatile suspended solids.
- MeSH
- anaerobióza * MeSH
- biopaliva * MeSH
- odpadní voda chemie MeSH
- sulfan MeSH
- Publikační typ
- časopisecké články MeSH
Energy consumption of municipal wastewater treatment plants can be reduced by the anaerobic pre-treatment of the main wastewater stream. After this pre-treatment, nitrogen can potentially be removed by partial nitritation and anammox (PN/A). Currently, the application of PN/A is limited to nitrogen-rich streams (>500 mg L(-1)) and temperatures 25-35 °C. But, anaerobically pretreated municipal wastewater is characterized by much lower nitrogen concentrations (20-100 mg L(-1)) and lower temperatures (10-25 °C). We operated PN/A under similar conditions: total ammonium nitrogen concentration 50 mg L(-1) and lab temperature (22 °C). PN/A was operated for 342 days in a 4 L moving bed biofilm reactor (MBBR). At 0.4 mg O2 L(-1), nitrogen removal rate 33 g N m(-3) day(-1) and 80 % total nitrogen removal efficiency was achieved. The capacity of the reactor was limited by low AOB activity. We observed significant anammox activity (40 g N m(-3) day(-1)) even at 12 °C, improving the applicability of PN/A for municipal wastewater treatment.
- MeSH
- amoniové sloučeniny chemie MeSH
- anaerobióza MeSH
- biofilmy MeSH
- bioreaktory MeSH
- čištění vody MeSH
- dusík chemie MeSH
- hybridizace in situ fluorescenční MeSH
- kyslík chemie MeSH
- nízká teplota MeSH
- odpad tekutý - odstraňování metody MeSH
- odpadní voda chemie MeSH
- teoretické modely MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Biogas, digested sludge and sludge liquor are the main products of anaerobic sludge digestion. Each of the products is influenced significantly by specific conditions of the digestion process. Therefore, any upgrade of the digestion technology must be considered with regard to quality changes in all products. Microaeration is one of the methods used for the improvement of biogas quality. Recently, microaeration has been proved to be a relatively simple and highly efficient biological method of sulfide removal in the anaerobic digestion of biosolids, but little attention has been paid to comparing the quality of digested sludge and sludge liquor in the anaerobic and microaerobic digestion and that is why this paper primarily deals with this area of research. The results of the long-term monitoring of digested sludge quality and sludge liquor quality in the anaerobic and microaerobic digesters suggest that products of both technologies are comparable. However, there are several parameters in which the 'microaerobic' products have a significantly better quality such as: sulfide (68% lower) and soluble chemical oxygen demand (COD) (33% lower) concentrations in the sludge liquor and the lower foaming potential of the digested sludge.
The anaerobic digestion of primary and waste activated sludge generates biogas that can be converted into energy to power the operation of a sewage wastewater treatment plant (WWTP). But can the biogas generated by anaerobic sludge digestion ever completely satisfy the electricity requirements of a WWTP with 'standard' energy consumption (i.e. industrial pollution not treated, no external organic substrate added)? With this question in mind, we optimized biogas production at Prague's Central Wastewater Treatment Plant in the following ways: enhanced primary sludge separation; thickened waste activated sludge; implemented a lysate centrifuge; increased operational temperature; improved digester mixing. With these optimizations, biogas production increased significantly to 12.5 m(3) per population equivalent per year. In turn, this led to an equally significant increase in specific energy production from approximately 15 to 23.5 kWh per population equivalent per year. We compared these full-scale results with those obtained from WWTPs that are already energy self-sufficient, but have exceptionally low energy consumption. Both our results and our analysis suggest that, with the correct optimization of anaerobic digestion technology, even WWTPs with 'standard' energy consumption can either attain or come close to attaining energy self-sufficiency.
- MeSH
- anaerobióza MeSH
- biopaliva MeSH
- měření biologické spotřeby kyslíku MeSH
- odpad tekutý - odstraňování přístrojové vybavení metody MeSH
- odpadní voda * MeSH
- odpadní vody MeSH
- zdroje energie * MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Česká republika MeSH
Anaerobic digestion is the only energy-positive technology widely used in wastewater treatment. Full-scale data prove that the anaerobic digestion of sewage sludge can produce biogas that covers a substantial amount of the energy consumption of a wastewater treatment plant (WWTP). In this paper, we discuss possibilities for improving the digestion efficiency and biogas production from sewage sludge. Typical specific energy consumptions of municipal WWTPs per population equivalent are compared with the potential specific production of biogas to find the required/optimal digestion efficiency. Examples of technological measures to achieve such efficiency are presented. Our findings show that even a municipal WWTP with secondary biological treatment located in a moderate climate can come close to energy self-sufficiency. However, they also show that such self-sufficiency is dependent on: (i) the strict optimization of the total energy consumption of the plant, and (ii) an increase in the specific biogas production from sewage sludge to values around 600 L per kg of supplied volatile solids.
- MeSH
- anaerobióza MeSH
- časové faktory MeSH
- odpad tekutý - odstraňování metody MeSH
- odpadní vody chemie MeSH
- zachování zdrojů energie metody MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Česká republika MeSH
Microaerobic alternative of anaerobic digestion offers many advantages especially when sulfide concentration in the digester is high. For better understanding of the microaerobic technology more detailed characterization of biomass activity is needed. Two equal digesters were operated under the same condition except of microaeration in one of them. During long term operation of anaerobic and microaerobic digesters the sludge quality and the biomass activity was monitored. The activity of sulfide oxidizing bacteria of microaerobic biomass was significantly higher in comparison with anaerobic biomass. The activity of sulfate reducing bacteria was comparable. The activity of methanogenic bacteria activity depended on sulfide concentration more than on microaeration. The extent of foaming problems was lower in the microaerobic than in the anaerobic digester.
- MeSH
- aerobní bakterie metabolismus MeSH
- anaerobní bakterie metabolismus MeSH
- bioreaktory mikrobiologie MeSH
- methan analýza MeSH
- odpadní vody chemie mikrobiologie MeSH
- oxidace-redukce MeSH
- průmyslová mikrobiologie MeSH
- sírany chemie MeSH
- sulfidy chemie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
The paper reviews results and experience of microaerobic experiments at both high and low sulphide concentrations and evaluates advantages and drawbacks of the anaerobic digestion of sludge in microaerobic conditions as regards biogas quality, digested sludge quality, organic pollutants biodegradability and methanogenic activity of biomass. The innovative microaerobic modification of the anaerobic sludge digestion technology was studied in both laboratory and full scale. Microaerobic conditions are obtained by dosing of a limited amount of the air into the liquid phase of the anaerobic digester. It was shown that anaerobic bacteria including methanogens can be active also in such system. In a mixed culture, even strict anaerobes can survive without inhibition, if the facultative microorganisms are able to consume the present oxygen quickly and fully. Until now, the microaerobic conditions were predominantly used for hydrogen sulphide removal from biogas. In the paper the role of the surplus oxygen was studied also at low sulphide concentration, when the oxygen is consumed in high extent for other processes beside sulphide oxidation.
