Determination the ammonium separating in ground water by using polyurethane-derived carrier with microbial film technique

In order to determine the ammonium treating efficiency, several factors were investigated, including: carrier size and dimension, the volume of carrier, ammonium concentration… which impact on nitrification rate by two (02) techniques: moving and fixed bed microbial film. The results indicated that with moving bed microbial film technique, the best size and dimension of carrier is a cube with 1x1x1 cm, the content of carrier is of 20% in volume. However, fixed bed microbial film technique is favored by the cube of 2x2x2 cm carrier, the content of 50% in volume.

MODERN AASPECTS OF A ROOT CANAL INSTRUMENTATION

The authors of the article consider various approaches to the preparation of the apical part of the root canal. They analyze the nature of the microbial flora of the channel, the peculiarities of its distribution within the channel and beyond. In addition, the authors note the role of root cement in the extracanal arrangement of the microbial film. The article provides an analysis of such concepts as “ensuring the apical patency” and “opening the apical foramen.” The differences between these concepts is emphasized, which is of fundamental importance both for determining the limits of the apical preparation and for understanding the essence of the pathological processes in the periodontal teeth with the preserved and destroyed apical constriction. Based on their own research and data from the world endodontic literature, the authors offer their recommendations on instrumentation of the cement canal depending on a particular clinical situation.

Evaluation of substrate uptake by microbial film in a gel-like medium

Mathematical model was developed to demonstrates the predominantly reaction controlled region and diffusion limited region for p 3 with high or large diffusion in this case, but when p = 0.3 the chemical reaction and diffusion onset occurred. The model developed illustrates the relationship between K₃C* and N/Nmax for various incremental steps of K2 L. The result obtained reveals that increase in K3C* resulted to an increase in N/ Nmax until an optimum value of N/Nmax was achieved after then the values remain constant with incremental value on K3C*. The Kinetics of substrate is dependent of K3C* as well as K2L values of the system, which in overall influence the substrate uptake by microbial film in gel- like medium.

Analysis of the Start-Up of Natural Bio-Film Colonization of Constructed Rapid Infiltration System

this paper studied the start-up of natural bio-film colonization under the conditions where wet-to-dry ratio was 1:6, hydraulic load was 0.8m3/m2·d, and water temperature was 10°C-15°C, it took 25d in total to become mature, after the success of bio-film colonization, the removal rate of COD and NH4+-N can be stabilized at 80%, and the removal rate of NH4+-N can reach 90% above. The microorganism was divided into the following stages during bio-film colonization: 1.Reversible adhesion of cell on the surface of the carrier, 2.Irreversible adhesion of cell on the surface of the carrier, 3.Division of cell adhering to the surface of the carrier and formation of microcolony adhering to the surface of the carrier, 4.Growth of microcolony adhering to the surface of the carrier to be mature bio-film with three-dimensional structure. The process of natural bio-film colonization can be judged comprehensively according to removal rate of NH4+-N and COD, effluent pH as well as color of microbial film.

Living biofouling-resistant membranes as a model for the beneficial use of engineered biofilms

Membrane systems are used increasingly for water treatment, recycling water from wastewater, during food processing, and energy production. They thus are a key technology to ensure water, energy, and food sustainability. However, biofouling, the build-up of microbes and their polymeric matrix, clogs these systems and reduces their efficiency. Realizing that a microbial film is inevitable, we engineered a beneficial biofilm that prevents membrane biofouling, limiting its own thickness by sensing the number of its cells that are present via a quorum-sensing circuit. The beneficial biofilm also prevents biofilm formation by deleterious bacteria by secreting nitric oxide, a general biofilm dispersal agent, as demonstrated by both short-term dead-end filtration and long-term cross-flow filtration tests. In addition, the beneficial biofilm was engineered to produce an epoxide hydrolase so that it efficiently removes the environmental pollutant epichlorohydrin. Thus, we have created a living biofouling-resistant membrane system that simultaneously reduces biofouling and provides a platform for biodegradation of persistent organic pollutants.

Corrosion Behaviors of 0Cr18Ni9 Stainless Steel under the Combination Action of Sulfate-Reducing Bacteria and V.natriegens

Advantage strains SRB and V.natriegens were obtained from the China East Sea for this study. Polarization curves, corrosion potential, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analyses were adopted in order to investigate the corrosion behaviors of 0Cr18Ni9 stainless steel under the combination action of anaerobic SRB and facultative anaerobic V.natriegens, The characteristics and mechanisms of microbial corrosion action in sea water were analyzed in this paper. The results show that SRB and V.natriegens promote each other’s growth when cultivated in the mixed microbe medium, in which the rate of corrosion is higher than that in the single microbe; Under the combined action of the mixed microbe, the microbial film gets wider and thicker, and corrosion products and metabolite are produced, which furthermore accelerates the passivation and pit corrosion to the 0Cr18Ni9 stainless steel.

Corrosion Behaviors of QSn4-3 under Two Kinds of Marine Advantage Bacteria Environment

Polarization curves, corrosion potential, scanning electron microscopy (SEM) were adopted to investigate the corrosion behaviors of QSn4-3 under two kinds of marine advantage bacteria (anaerobic SRB and facultative anaerobic Vibrio natriegens) environment. The results show that the microbial film has some effects on inhibiting corrosion of QSn4-3 at the early stage of corrosion; the existence of marine microorganisms accelerates the corrosion process of QSn4-3; the combined action of SRB and V.natriegens accelerates the corrosion obviously and QSn4-3 coupon is more prone to pitting corrosion.