Biosorption of Cu(Ⅱ) on extracellular polymers from Bacillus sp.F19

Biosorption can be an effective process for the removal of heavy metals from aqueous solutions.The adsorption of Cu(Ⅱ) from aqueous solution on the extracellular polymers (EPS) from Bacillus sp.(named MBFF19) with respect to pH,incubation time,concentration of initial Cu(Ⅱ),and biosorbent dose was studied.Biosorption of Cu(Ⅱ) is highly pH dependent.The maximum uptake of Cu(Ⅱ) (89.62 mg/g) was obtained at pH 4.8.Biosorption equilibrium was established in approximately 10 min.The correlation coeffcient of mor...

Characterization of an extracellular polysaccharide produced by Bacillus sp.RL-2

A strain secreting a strongly acidic polysaccharide flocculating agent was isolated from activated sludge, and identified as Bacillus brevis. The bioflocculant was produced by RL-2 during the late logarithmic growth in the batch culture and was recovered from supernatant by ethanol precipitation. The bioflocculant is thermo-stable as its activity remains stable after heated at 100 °C for 45 min. Its flocculating activity with kaolin suspensions was stimulated by the addition of Ca2+, Al3+ and Cu2+. The flocculant consists of glucose, mannose, and galacturonic acid. Its average molecular mass was estimated to be approximately 2.86×105 by the method of viscosity. The flocculant aggregates various inorganic and organic compounds in solution.

Influence of different substrates on the formation and characteristics of aerobic granules in sequencing batch reactors

The effects of different substrates on the aerobic granulation process were studied using laboratory-scale sequencing batch reactors （SBRs）. Four parallel granules sequencing batch reactors （GSBR）： R1, R2, R3, and R4 were fed with acetate, glucose, peptone and fecula, respectively. Stable aerobic granules were successfully cultivated in R1, R2, R4, and smaller granules less than 500 μm were formed in R3. Morphology and the physic-chemical characteristics of aerobic granules fed with different carbon substrates were investigated by the four reactors operated under the same pressure. The aerobic granules in the four reactors were observed and found that peptone was the most stable one due to its good settleability even after a sludge age as short as 10 d. A strong correlation was testified between the characteristics of aerobic granules and the properties of carbon substrates. The stability of aerobic granules was affected by extracellular polymer substances （EPS） derived from microorganism growth during feast time fed with different carbon substrates, and the influence of the property of storage substance was greater than that of its quantity. Optimal carbon substrates, which are helpful in the cultivation and retention of well-settling granules and in the enhancement of the overall ability of the aerobic granules reactors, were found.

Transformation of iron in pure culture process of extremely acidophilic microorganisms

Jarosite and extracellular polymer substance generated during pure culture and bioleaching process have been widely accepted the main transformation of decreasing iron in the medium.In the present work,acidophilus bioleaching organisms Ferroplasma thermophilum,Leptospirillum ferriphilum and Acidithioobacillus ferrooxidans were cultured.It was found that they can live in low pH environment,and more than10particles in each cell intracellular nano-particles are synthesized in the cells.By analyzing the morphology and chemical composition of nano-particles,they were found to contain iron,and the three microorganisms belonged to high-yielding strains.The results show that the transformation of the decreasing iron ions is not only generating jarosite,but also taken into cells and synthesizing ferruginous nano-particles.

Effect of Sludge Retention Time on the Fate of Proteins and Polysaccharides in AAO Process

Effect of sludge retention time( SRT) on the removal of potential and polysaccharides in an anaerobic / anoxic / aerobic( AAO) process was investigated. The Lowry method and anthrone method were used to detect proteins and polysaccharides. Total removal efficiency of proteins at SRT of 10 to 25 d in the AAO system was higher than 90%. Polysaccharides removal efficiencies were above 80% when SRT was increased from 15 to 25 d,whereas only 81% of polysaccharides was removed at SRT of 10 d. The biodegradation part of proteins and polysaccharides increased from87. 40% to 93% and from 74. 22% to 86. 94% with increasing SRTs.The ratios of polysaccharides and proteins in extracellular polymer substances( EPSs) were around 1. 5-3 in different SRTs. As SRT increasing,polysaccharides and proteins discharged with residual sludge decreased gradually. The amount of EPSs decreased with increasing SRTs.