The difference of morphological characteristics and population structure in PAO and DPAOgranular sludges.

We examined how long-term operation of anaerobic-oxic and anaerobic-anoxic sequencing batch reactors (SBRs) affects the enhanced biological phosphorus removal (EBPR) performance and sludge characteristics. The microbial characteristics of phosphorus accumulating organism (PAO) and denitrifying PAO (DPAO) sludge were also analyzed through a quantitative analysis of microbial community structure. Compared with the initial stage of operation characterized by unstable EBPR, both PAO and DPAO SBR produced a stable EBPR performance after about 100-day operation.

Comparison of biochemical characteristics between PAO and DPAO sludges.

A successful enhanced biological phosphorus removal (EBPR) was observed in both anaerobic-aerobic sequencing batch reactor (An-Ox SBR) to induce growth of phosphorus accumulating organism (PAO) and anaerobic-anoxic (An-Ax) SBR to induce growth of denitrifying PAO (DPAO). Although the EBPR performance of An-Ox SBR was higher by 11.3% than that of An-Ax SBR, specific phosphorus release rates in the An-Ax SBR (22.

Anoxic gas recirculation system for fouling control in anoxic membrane reactor.

Anoxic gas recirculation system was applied to control the membrane fouling in pilot-scale 4-stage anoxic membrane bioreactor (MBR). In the anaerobic-anoxic-anoxic-aerobic flow scheme, hydrophilic polytetrafluoroethylene (PTFE) membrane (0.2 μm, 7.

Transfer of antibiotic resistance plasmids in pure and activated sludge cultures in the presence of environmentally representative micro-contaminant concentrations.

The presence of antibiotics in the natural environment has been a growing issue. This presence could also account for the influence that affects microorganisms in such a way that they develop resistance against these antibiotics. The aim of this study was to evaluate whether the antibiotic resistant gene (ARG) plasmid transfer can be facilitated by the impact of 1) environmentally representative micro-contaminant concentrations in ppb (part per billion) levels and 2) donor-recipient microbial complexity (pure vs.

Microbial structure and community of RBC biofilm removing nitrate and phosphorus from domestic wastewater.

Using a rotating biological contactor modified with a sequencing bath reactor system (SBRBC) designed and operated to remove phosphate and nitrogen, the microbial community structure of the biofilm from the SBRBC system was characterized based on the extracellular polymeric substance (EPS) constituents, electron microscopy, and molecular techniques. Protein and carbohydrate were identified as the major EPS constituents at three different biofilm thicknesses, where the amount of EPS and bacterial cell number were highest in the initial thickness of 0-100 microm. However, the percent of carbohydrate in the total amount of EPS decreased by about 11.

Effect of biologically mediated pH change on phosphorus removal in BNR system for piggery waste treatment.

Since applicable amount of animal waste to farm land has been greatly reduced because of the nutrient overload, nitrogen and phosphorus removal from animal waste has received a great attention. This study was conducted to evaluate how phosphorus was removed during biological nutrient removal (BNR) from piggery waste using laboratory and full scale units operated at 25 to 40 degrees C. The phosphorus removal was performed by chemical precipitation with struvite and hydroxyapatite (HAP), cellular formation, it is basically related with pH and organic and nitrogen loads resulting in influent COD/N ratios.

Full-scale experience for nitrogen removal from piggery waste.

The nitrogen-removal performances of three full-scale piggery wastewater treatment plants, with different organic and nitrogen loads, at the capacity ranges of 95 to 130 m3/d, were compared in this study. Plants 1 and 2 can be characterized as the modification of anoxic-aerobic operating systems, while an anaerobic and anoxic-aerobic system was used in plant 3. The influent piggery wastewater concentration for plant 1 was relatively lower, but with higher organic and nitrogen loads, resulting in higher chemical oxygen demand (COD) and ammonium-nitrogen in effluent.

Removal of ammonium from tannery wastewater by electrochemical treatment.

The removal of ammonium from coagulated tannery wastewaters was investigated by an electrochemical method using Ti/IrO2 as an anode. Operating variables including the current density, pH and chloride concentration were considered in order to determine their effect on the ammonium removal efficiency. A maximum ammonium removal rate of 78.

Practical aspects of nitrogen and phosphorous removal with floating media SBBR.

Practical aspect on the application of floating media for the sequencing batch biofilm reactor (SBBR) has not been studied in detail, especially focused on settling step, nutrient removal and temperature effects. Two types of floating media (sponge and plastic) had been examined for SBBR operation with sewage. Based on the observations with various experimental variables including temperature, media volume, operating methods, both SBBR units with sponge and plastic media generally produced a stable nitrified effluent, but depicted unstable phosphorus removal.