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The anaerobic baffled reactor (ABR) possesses many advantages such as high removal efficiency, outstanding working stability, and lower operating cost. In this essay, four reactors of equal effective volume (56.4 L) that were designed with three, four, five, and six compartments were adopted to investigate the flow patterns of the ABR through the tracer pulse stimulus-response technique and cold-model tests. The dead space decreases with the increase in the ABR compartments; specifically, the mean dead space induced by biomass and hydraulic behavior in 3-, 4-, 5-, and 6-compartment ABRs were 6.40, 5, 3.30, and 3%, respectively. In addition, the increase in ABR compartments also resulted in the decrease in back-mixing and 1/Pez values (from 0.118 to 0.060), which made the fluid in the reactor approach to the plug flow state. Analysis of the theoretical optimal number of ABR compartments shows that, the series number (N) of compartments shall be kept at 4 ≤ N ≤ 5 when the removal efficiency of the r...

Soluble microbial products (SMP) have been demonstrated as a primary obstacle for the widespread application of membrane bioreactor (MBR). This study has investigated the effects of micro-organism growth phase (MGPs) on the accumulation and characteristics of SMP in MBR. The results showed that there were three MGPs in the experiment, including exponential growth phase (EGP), deceleration growth phase (DGP), and stationary growth phase (SGP), respectively. Polysaccharides and proteins in SMP were steadily increased in the EGP. While in the DGP, the SMP were increased firstly and then decreased sharply. Finally, the concentrations of SMP maintained at a low steady level in the SGP. Furthermore, the biomass associated products (BAP) batch experiment showed that the production potential of SMP was the largest in the DGP. The percentage of SMP (>30 kDa) was remarkably increased, then dropped due to abruptly decreasing production potential of BAP and degradation by acclimated micro-organisms. The resul...

Oxidative stress parameters and some antioxidant defense systems in the liver of Carassius auratus exposed to glyphosate and its formulation (Roundup®) have been studied. Fish were exposed to glyphosate and its formulation at concentrations of 0.032, 0.16, 0.8, and 4.0 mg L−1, all calculated on glyphosate basis, for 11 days. Hydroxyl radical generation as determined by electron spin resonance spectroscopy of its spin-adduct with α-phenyl-t-butyl nitrone increased with the concentration of Roundup®. Superoxide dismutase activities were decreased relative to control by 21%–46% when exposed to glyphosate and 45%–52% when exposed to Roundup®, suggesting that the formulation is more toxic than glyphosate alone. Catalase showed no difference between both groups.

Phosphine (PH3) is a natural constituent in phosphorus (P) chemical cycles. The discovery of phosphine will shed new light on the mechanisms of P supplement and biogeochemical cycles. Since phosphine is converted to phosphate after complex oxidation via hypophosphite and phosphite, if it were present in the water column, understanding its production and emission could enhance our understanding of P speciation. Assuming that phosphine in the gas phase is an ideal gas and at equilibrium between water and gas interface, phosphine in water solution can be quantified from the equilibrated concentration in gas phase using the Henry's Law. Application of this approach to Lake Taihu, China, phosphine in unfiltered and filtered water samples (0.45 μm) was analysed. Results showed that phosphine was universally present in Lake Taihu water. Phosphine concentration in unfiltered water ranged from 0.16 to 1.11 pg L−1, and was much less (0.01 to 0.04 pg L−1) in filtered samples. Over 90% of phosphine was adsorbed onto ...