Grundlagenuntersuchungen zur komplexen mikrobiellen Reinigung von Kohleprozesswaessern Abschlussbericht

Aerobic microbiological processes applicated to waste water treatment of coal pyrolysis sewages lead to heavily degradable abiotic oxidation products. Some substituted phenols and toluenes are not degradable, the microbiological oxidation of ammonia is inhibited. The present investigation aimed at ascertaining the anaerbobic degradation of substituted phenols and toluenes resp. and at checking the possibility of the simultaneous degradation and nitrification of N-heterocyclics by a nitrifying coculture. As a result more effective microbiological processes for waste water treatment of coal pyrolysis sewages should be derived. The experiments were carried out in lab scale with enrichment cultures (anaerobic experiments: Isolated from river sediments, nitrification ones: Isolated from an industrial waste water plant). As a result we were able to show - contrary to reports in the literature - that 13 different substituted phenols and toluens are anaerobically degradable. The degradation kinetics was determined for all isomers of dihydroxytoluene and a connection was derived between the degradation rate and the chemical structure. Furthermore we are able to show the aerobic degradation of pyridine and imidazol and the simultaneous nitrification of the ring-nitrogen when using an adapted nitrifying biomass. The degradation was inhibited at a concentration of 600 mg/l imidazol and at the same time an accumulation of nitrite can be observed. The results of this work will be the basis for new projects in industrial waste water and drinking water treatment. (orig.)Werden Abwaesser aus der thermischen Kohlebehandlung mikrobiologisch aerob behandelt, bilden sich aus den phenolischen Inhaltsstoffen schwerabbaubare abiotische Oxidationsprodukte. Einige substituierte Phenole und Toluole werden nicht abbgebaut, die mikrobiologische Ammoniakoxidation wird inhibiert. Die durchgefuehrten Untersuchungen sollten dem Nachweis des anaeroben Abbaus der unterschiedlichsten Phenole bzw. Toluole dienen sowie der Ueberpruefung der Frage, ob waehrend der Nitrifikation ein mikrobieller Abbau von N-Heterozyklen nachgewiesen werden kann. Ziel ist die Vorbereitung neuer effektiver mikrobiologischer Verfahren zur Reinigung von Kohlepyrolysewaessern. Die Untersuchungen wurden im Labormassstab mit Anreicherungskulturen (anaerob aus Flusssedimenten, zur Nitrifikation aus einer Industrieabwasseranlage) durchgefuehrt. Im Ergebnis der Laboruntersuchungen konnte gezeigt werden, dass entgegen der bisherigen Kenntnisse fuer 13 unterschiedliche Phenole und Toluole ein anaerober mikrobieller Abbau nachgewiesen werden konnte. Fuer alle Isomeren des Dihydroxytoluols wurde die Abbaukinetik bestimmt und ein Zusammenhang zwischen Substitution und Abbaugeschwindigkeit abgeleitet. Bei Verwendung einer adaptierten Nitrifikationbiomasse wurde der Abbau von Pyridin und Imidazol mit gleichzeitiger Nitrifikation des Ringstickstoffs nachgewiesen. Bei 600 mg/l Imidazol ist eine Verzoegerung des Abbaus zu bemerken, es kommt zu einer Anreicherung von Nitrit. Die gewonnenen Erkenntnisse sind die Grundlage neuer Projekte zur Industrieabwasserreeinigung bzw. zur Trinkwasseraufbereitung. (orig.)SIGLEAvailable from TIB Hannover: D.Dt.F.QN1(20,22) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman

Comparative laboratory-scale study of resorcinol and nitrogen removal in different treatment wetlands

The current knowledge on the treatment of resorcinol-and nitrogen-containing wastewater in different treatment wetlands is limited. This study investigated three laboratory-scale treatment wetlands, namely, floating wetland, planted wetland and unplanted wetland, treating artificial wastewater containing resorcinol and ammonium. Under the inflow resorcinol concentration of 10 mg/L, these wetlands exhibited a removal efficiency of approximately 94% on average, with a specific area removal rate of 260 mg/(m2·d), regardless of wetland type and the presence of plants. These results suggest that treatment of resorcinol-containing wastewater by wetlands is a low-cost and ecological alternative. Compared with the dynamics of ammonium in the unplanted wetland, the high ammonium removal rate (&gt;95%) observed for the planted and floating wetlands strongly indicated that the plants stimulated ammonium oxidation processes mainly by releasing oxygen from the roots. Acidification at pH 3, which can be attributed to an active nitrification process and the secretion of hydrogen ions by the plant roots, was observed in the floating wetland. The low pH buffer capacity could be caused by the low content of dissolved inorganic carbonates, and the use of substrate may act as a barrier to prevent rapid diffusion of carbon dioxide from the pore water to the atmosphere. The significant nitrate accumulation rate of 20 mg/L noted in the floating wetland indicated a limited denitrification process due to the high redox condition (600 mV). A better oxygenated condition for the floating wetland is beneficial to oxidation removal of organic compounds and ammonium, but it may not be good for such reduction processes as denitrification.</jats:p

Regulation of aerobic granular sludge reformulation after granular sludge broken: Effect of poly aluminum chloride (PAC)

The present study focuses on the effect of poly aluminum chloride (PAC) on the re-formation of aerobic granular sludge after its rupture. The morphological changes, physical characteristics such as SVI, mechanical strength and surface properties of aerobic granular sludge during the re-formation process of broken granules were investigated. Moreover, components (protein (PN), polysaccharides (PS)) and distributions (soluble, loosely-bound (LB), tightly-bound (TB)) of extracellular polymeric substances (EPS) in sludge flocs were taken into consideration. It was found that the effect of charge neutralization and bridging induced by PAC treatment improved the surface properties of sludge, the re-formed granules had a larger size, more compact structure and that the removal performance of pollutants after chemical coagulation had improved. The results of correlation analysis demonstrated that PN in EPS correlated well with the surface characteristics and settling ability of sludge flocs, and PAC treatment strengthened the influence, further accelerated the reformation of granular sludge.</p

Nitrogen transforming community in a horizontal subsurface-flow constructed wetland

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Poly aluminum chloride (PAC) enhanced formation of aerobic granules:Coupling process between physicochemical–biochemical effects

Transforming conventional flocculent sludge to aerobic granular sludge is drawing increasing global interest in a quest for an efficient and innovative technology in wastewater treatment. However, long start-up time and low granule stability are the main challenging issues for its application. In this study, long-term and short-term PAC feeding strategies were applied in parallel to enhance the sludge granulation and with the aim to figure out the temporal effect of PAC during the whole process. Nevertheless, both of them identified to allow a rapid start-up formation of aerobic granules with better performances in physicochemical characteristics. More extracellular polymeric substances (EPS) were secreted in all PAC-fed reactors, especially for polysaccharides. By using enzymatic hydrolysis, factors which account for the flocculating ability and stability of granules were identified. Notably, the correlation between them was also revealed. Based on these findings, dosage of PAC played a positive role mainly during the start-up period (first 15&nbsp;days) of the aerobic granules formation, extending its dosing time made no significant sense. The granules formed under this condition were the result of physicochemical&ndash;biochemical effects coupling process.</p

Effect of nitrate on sulphur transformations depending on carbon load in laboratory-scale wetlands treating artificial sewage

Two laboratory-scale constructed wetlands planted with Juncus effusus were used to investigate the dynamics of sulphur transformations under varying nitrate and organic carbon loads as well as its interactions with microbial carbon and nitrogen transformations. The removal of dissolved organic carbon was obtained to be around 65-87% with specific removal load of 1.40-2.63 g/m2 d. 94% of nitrate removal (under inflow concentration of 15 mg/L) irrespective of organic carbon loads indicated a highly active denitrification process in wetlands. Sulphate reduction was performed at a high level of 83% in a low redox potential (about -300 mV) under condition of inflow organic carbon concentration of 50 mg/L. The dosage of nitrate in the inflow can strongly hinder the process ofdissimilatory microbial sulphate. The coexist of sulphide with concentration of 1.65-2.65 mg/L and elemental sulphur of 0.17-2.18 mg/L in the pore water of wetlands demonstrated a simultaneous occurrence of microbial sulphate reduction and sulphide oxidation. A lower ammonium oxidation removal was initiated, which was probably caused by the toxic effect of sulphide with concentration of about 3 mg/L in the pore water. The sulphide concentration in the pore water was highly exponentially correlated with the redox potential, indicating the control of sulphide in wetlands could be performed by the adjustment of redox potential via aeration and/or nitrate dosage.</jats:p

Anaerober Aromatenabbau mittels thermophiler Mikroorganismen Abschlussbericht

The coal processing industry produces hot phenolic effluents. The autooxidation products formed during cooling of the effluents in air are hardly biodegradable. In consequence, there is a practical interest in fermentation under thermophilic anaerobic (methanogenic) conditions. Practical and scientific basic knowledge is hardly existent in this field so far. The fermentability of a phenolic effluent of a coal pressure gasification process was proved also in thermophilic conditions. CSB was reduced by 50%, aromatic hydrocarbons only by 30%. The values achieved in mesophilic conditions were 75% and 55%, respectively. The fermentability of a number of aromatic hydrocarbons was investigated under thermophilic methanogenic conditions. (orig./EF)In der kohleveredelnden Industrie fallen heisse phenolische Abwaesser an. Die Autoxidationsprodukte, die sich bei der Abkuehlung der Abwaesser an der Luft bilden, sind biologisch schwer abbaubar. Deshalb besteht ein praktisches Interesse, solche Abwaesser unter thermophilen anaeroben (methanogenen) Bedingungen zu fermentieren. Praktische und wissenschaftliche Grundlagenkenntnisse fehlen hierzu bisher weitgehend. Am Beispiel eines Phenolduennwassers der Kohledruckvergasung konnte dessen Fermentierbarkeit auch unter thermophilen Bedingungen nachgewiesen werden. Die CSB-Abnahme betrug 50%; der Abbau der aromatischen Inhaltsstoffe erfolgte nur zu ca. 30%. Die entsprechenden erreichbaren Werte bei der Fermentation unter mesophilen Bedingungen betrugen hierzu 75 bzw. 55%. Es wurde die Fermentierbarkeit einer Reihe aromatischer Verbindungen unter thermophilen methanogenen Bedingungen geprueft. (orig./EF)Available from TIB Hannover: D.Dt.F. QN1(7,3) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman