Enhanced flocculation of two bioflocculation-producing bacteria by secretion of Philodina erythrophthalma.

Bdelloid rotifer are reported to play a promoting role in microbial aggregation and floc formation in activated sludge systems; however, the mechanisms involved in this process are unclear. This study explores the effect of a rotifer secretion (RS) from the species Philodina erythrophthalma on the flocculation and growth of two bioflocculation-producing bacteria isolated from activated sludge. Results show that although the secretion has weak bioflocculability in itself, it can significantly enhance the flocculability of bioflocculation-producing bacteria and promote formation of microbial aggregation and floc.

Rapid start-up of a nitrifying reactor using aerobic granular sludge as seed sludge.

In this study, the effectiveness of aerobic granular sludge as seed sludge for rapid start-up of nitrifying processes was investigated using a laboratory-scale continuous stirred-tank reactor (CSTR) fed with completely inorganic wastewater which contained a high concentration of ammonia. Even when a large amount of granular biomass was inoculated in the reactor, and the characteristics of influent wastewater were abruptly changed, excess biomass washout was not observed, and biomass concentration was kept high at the start-up period due to high settling ability of the aerobic granular sludge. As a result, an ammonia removal rate immediately increased and reached more than 1.

Foaming control by automatic carbon source adjustment using an ORP profile in sequencing batch reactors for enhanced nitrogen removal in swine wastewater treatment.

Incomplete denitrification and ammonia accumulation were found to cause proliferation of filamentous microorganisms in sequencing batch reactors (SBRs) for swine wastewater treatment. Foaming was observed in response to the accumulation of 115.2 and 12.

Biodegradation of chlordane and hexachlorobenzenes in river sediment.

Contamination of river sediments by persistent organic pollutants (POPs) is a worldwide concern, and microbial degradation is regarded as an important process for removal of POPs from river sediments. To date, there is still a lack of systematic study on chlordane biodegradation in river sediments, and the information on hexachlorobenzene (HCB) biodegradation in river sediments is very limited in Japan. We investigated the anaerobic biodegradation potential of trans-chlordane (TC), cis-chlordane (CC), and HCB in sediment samples collected at three sites along the Kamogawa River in Saitama Prefecture, Japan.

Anaerobic/oxic/anoxic granular sludge process as an effective nutrient removal process utilizing denitrifying polyphosphate-accumulating organisms.

In a biological nutrient removal (BNR) process, the utilization of denitrifying polyphosphate-accumulating organisms (DNPAOs) has many advantages such as effective use of organic carbon substrates and low sludge production. As a suitable process for the utilization of DNPAOs in BNR, an anaerobic/oxic/anoxic granular sludge (AOAGS) process was proposed in this study. In spite of performing aeration for nitrifying bacteria, the AOAGS process can create anaerobic/anoxic conditions suitable for the cultivation of DNPAOs because anoxic zones exist inside the granular sludge in the oxic phase.

Effectiveness of oxidation-reduction potential and pH as monitoring and control parameters for nitrogen removal in swine wastewater treatment by sequencing batch reactors.

Two bench-scale sequencing batch reactors (SBRs) were operated in a fixed hydraulic retention time study to investigate the effectiveness of oxidation-reduction potential (ORP), pH and dissolved oxygen as parameters for indicating denitrification followed by nitrification in SBRs for swine wastewater treatment. The ORP and pH profiles were monitored and evaluated under different denitrification and nitrification conditions with and without a supplemental carbon source. With a low C/N ratio, and using a suitable C/N ratio adjustment control, ORP and pH could be used as monitoring and control parameters in both the anoxic and oxic phases for practical swine wastewater treatment.

Aerobic biodegradation behavior of nonylphenol polyethoxylates and their metabolites in the presence of organic matter.

In this paper, the aerobic biodegradation behavior of nonylphenol polyethoxylates (NPnEOs) with ethoxy (EO) units of specific lengths, which were fractionated using high-performance liquid chromatography(HPLC) with photodiode array detection, was studied in the presence of different types of organic materials. NPnEOs and their related metabolites under a modified OECD 301E biodegradation test were monitored using liquid chromatography/mass spectrometry (LC/MS) and gas chromatography/mass spectrometry (GC/MS). Biodegradation tests in the presence of organic matters, such as methanol, glucose, and yeast extract, showed the formation of the corresponding nonylphenol polyethoxy carboxylates by the oxidation of the terminal alcoholic group.

Integrated real-time control strategy for nitrogen removal in swine wastewater treatment using sequencing batch reactors.

A new integrated real-time control system was designed and operated with fluctuating influent loads for swine wastewater treatment. The system was operated with automatic addition control of an external carbon source, using real-time control technology, which utilized the oxidation-reduction potential (ORP) and the pH as parameters to control the anoxic phase and oxic phase, respectively. The fluctuations in swine wastewater concentration are extreme; an influent with a low C/N ratio is deficient in organic carbon, and a low carbon source level can limit the overall biological denitrification process.