A high-rate and stable nitrogen removal from reject water in a full-scale two-stage AMX® system.

This paper reports long-term performance of a two-stage AMX® system with a capacity of 70 m3/d treating actual reject water. An air-lift granulation reactor performed partial nitritation (PN-AGR) at an average nitrogen loading rate (NLR) of 3.1 kgN/m3-d, producing an average effluent NO2--N/NH4+-N ratio of 1.04. The average nitrogen removal rate of the system was 3.91 kgN/m3-d following an anaerobic ammonium oxidation (Anammox) stage moving bed biofilm reactor (A-MBBR). Although the total nitrogen concentrations in the reject water fluctuated seasonally, overall nitrogen removal efficiency (NRE) of the two-stage AMX® system was very stable at over 87%. The two-stage AMX® system, consisting of a PN-AGR followed by an A-MBBR, operated at a stable NLR of 1.86 kgN/m3-d (1.64 kgN/m3-d including the intermediate tank), which is 1.8 times higher (1.6 times including the intermediate tank) than other commercialized single-stage partial nitritation/Anammox (PN/A) processes (which operate at a NLR of about 1 kgN/m3-d). The PN-AGR was affected by high influent total suspended solids (TSS) loads, but was able to recover within a short period of 4 days, which confirmed that the two-stage PN/A process is resilient to TSS load fluctuations.

Anammox biomass carrying efficiency of polyethylene non-woven sheets as a carrier material.

To access the effects of the surface modification and fabric structure of polyethylene (PE) non-woven fabric sheets on retaining the attachment efficiency of anammox biomass, three different non-woven sheets were prepared and inserted in an anammox reactor. The hydrophobic surface modification with 10% KMnO4 and gelatin did not improve the attachment efficiency of the anammox biomass on the surface of the PE non-woven fibers. Densely packed PE-755 having the highest specific surface area to volume ratio (SA/V) (755) retained 221.4 mg biomass per unit sheet, whereas PE-181 having the lowest SA/V (181) retained only 66.4 mg biomass per unit. Accordingly, the volumetric anammox activity of non-woven sheet PE-755 was the highest among the three PE non-woven sheets because of the strong positive relationship between the specific anammox activity and biomass amount (R = 0.835, P < .01). The specific surface area to volume ratio (cm2 cm-3) as well as the bulk density should be considered as important parameters for the selection of non-woven biocarriers for anammox biomass.

Assay of In Vivo Chromium with a Hollow-fiber Dialysis Sensor.

The analytical in vivo chromium ion was searched for using a voltammetric hollow-fiber dialysis sensor via square wave stripping voltammetry (SW) , cyclic voltammetry (CV) , and chronoamperometry. Under optimum parameters, the analytical results indicated linear working ranges of 50~400 mg/l CV and 10~80 µg/l SW within a 30-sec accumulation time. The analytical detection limit (S/N) was 6.0 µg/l. The developed method can be applied to in vivo tissues and in ex vivo toxicity assay, as well as to other materials that require chromium analysis.