Candidatus 'Accumulibacter phosphatis' ('Accumulibacter') is known as polyphosphate-accumulating organism found in the enhanced biological phosphorus removal (EBPR) activated sludge processes. 'Accumulibacter' is a yet-to-be isolated bacteria, and the growth of 'Accumulibacter' under aerobic conditions is still unknown. In this study, the potential for growth of 'Accumulibacter' in an aerobic shaking culture was evaluated. Activated sludge samples from a laboratory-scale EBPR reactor were incubated for 48 hours under different conditions (pH, temperature and carbon source), and the multiplication of the 'Accumulibacter' 16S rRNA gene was quantified by using quantitative real-time PCR (polymerase chain reaction). The gene showed statistically significant increase when the carbon source in the medium was glucose, the initial pH was 10.0 and the temperature was 20 °C (p > 0.05, n=9). Results in this study showed that 'Accumulibacter' most probably has the potential to grow in an aerobic shaking culture. The obtained results are desired to provide a hint for the successful isolation of 'Accumulibacter'.
PIP tin balls effectively decolorized azo dyes in citric acid solution and produced p-aminobenzene sulfonic acid (ABS) and 1-amino-2-naphthol (1A2N) stoichiometrically by reductive cleavage of Orange II. We performed the decolorization of Orange II under stirring condition to investigate the effect of dissolved oxygen. The decolorization rates estimated using pseudo first-order reactions under anaerobic conditions were significantly higher than those under aerobic conditions. The reductive cleavage of Orange II was inactivated after repeated decolorization reactions in the presence of oxygen. This was associated with the formation of a white precipitate on the surface of the inactivated PIP tin balls, which formed a protective film of oxidized Sn compounds. The surface-area-normalized first-order reaction rate constant (kSA) for 0.3 mM Orange II, was 0.22 (l m-2 min-1), which was similar to the previously reported value for Orange II decolorization using zero-valent iron powder. Oxidation of metallic tin in the structure of PIP tin balls was considered to be an important factor for the reaction mechanism in the presence of citric acid.
Ozonation combined with electrolysis (ozone-electrolysis), ozonation alone and electrolysis alone were applied to the treatment of a paper and pulp mill wastewater for the decolorization and removal of chemical oxygen demand (COD). Electrolysis alone was ineffective in treating the paper and pulp mill wastewater. Both ozone-electrolysis and ozonation alone were effective in removing chromaticity, but produced white suspended solids. The production of the solid by ozone-electrolysis was smaller than by ozonation alone. The ozone-electrolysis demonstrated more rapid removal of COD and higher ozone effectivity than the ozonation alone. Furthermore, ozone-electrolysis was the most useful method to transform organic compounds into more oxygenated ones of the three.
Ho Tay (West Lake) in Hanoi, Vietnam receives wastewater from the city center and the surrounding residential areas, which can cause both eutrophication and enrichment of toxic heavy metals in the lake ecosystem. The aim of this study is to evaluate the recent trends of metal contamination in this lake from their spatial (horizontal and vertical) distributions in the lake sediments. Sediment cores with up to 70 cm in depth were sampled from four locations in the lake and analyzed for heavy metals (Cd, Cr, Cu, Mn, Ni, Pb and Zn) including a metalloid (As) and total organic carbon (TOC). High concentrations of the metals (except for Mn) and TOC have accumulated in sediment at the site where an inlet of sewage from the city center was located nearby. Increasing trends of the metal contents in the sediment profile toward the surface at the sites distant from the sewage inlets imply that the loads of these metals into this lake have been continuously increasing. In addition, Pb isotopic ratios in sediment profile could be used as an indicator of anthropogenic Pb pollution in the lake.
The degradation of 10 selected pharmaceutically active compounds (PhACs) by whole fungal culture Trametes versicolor, culture filtrates and commercial laccase preparation was conducted. Complete removal of diclofenac (DCF), naproxen (NPX), indomethacin (IDM), ibuprofen (IBP), and fenoprofen (FEP) and partial degradation of other selected PhACs were observed after 48 hours of incubation with the 7-day-old liquid fungal culture both in the presence and absence of ABTS (2,2'-azino-bis(3-ethyl-benzothiazoline-6-sulfonic acid)) as a laccase-mediator. The catalytic activity of laccase in the degradation of selected PhACs was examined for both crude and commercial extracellular laccase preparations. The results showed that laccase preferentially removed DCF, NPX and IDM among the target PhACs removed by the whole fungal culture. Intracellular enzymes may be involved in the degradation of ketoprofen (KEP), clofibric acid (CA), carbamazepine (CBZ), propyphenazone (PPZ), fenoprofen (FEP) and gemfibrozil (GFZ). The removal of most selected PhACs was increased with the increase in laccase activity. The presence of redox mediators such as ABTS and HBT (1-hyroxybenzotriazole) promoted the degradation of selected PhACs, in which complete removal of DCF, NPX and IDM was observed after 3 hours of incubation with laccase activity (2000 U/L) in the presence of ABTS/HBT. The degradation spectrum by laccase for ionic PhACs with nitrogen-containing structure was quite different from that of the activated sludge process.
It is well known that it takes long time to stabilize landfill and meet the standard for leachate after landfilling is stopped. Moreover, the time required to meet the standard is not predicted. In this research, the rapid small-scale column test (RSSCT) was applied and was found to predict the dissolved organic carbon (DOC) leaching from municipal solid waste incineration bottom ash in a simulated landfill site. Acid washing with hydrochloric acid remarkably reduced the DOC leaching from bottom ash. According to the RSCCT, it was estimated that the acid washing would reduce the time for DOC stabilization of bottom ash by about 80% in a simulated landfill situation.