Biological preparation and application of poly-ferric sulfate flocculant

A novel inorganic polymer flocculant,poly-ferric sulfate（BPFS） was prepared by oxidation of ferrous sulfate using domestic Thiobacillus ferrooxidans（T·f） under acid condition.The optimal conditions for the preparation were pH value of 1.5,（NH4）2SO4 dosage of 0.5 g/L,initial Fe2＋ concentration of 45g/L,inoculum 10%,rotating speed of 120 r/min,reaction time of 5-6 d and reaction temperature of 30 ℃.Under the optimal conditions,the BPFS product with pH value of 1.5-2.2,basicity of 17.5%-22.7% and total iron content of 43.87-45.24 g/L was obtained.The application of the BPFS to three wastewaters was carried out,and the removal efficiencies of COD,decolorization and Zn2＋ by BPFS can be reached 70%,90% and 99%,respectively.The result suggests that the BPFS is an excellent flocculant for water treatment.

Industrial waste utilization method： producing poly-ferric sulfate （PFS） from sodium-jarosite residue

Sodium-jarosite is a type of industrial waste that results from hydrometallurgy and inorganic chemical production. The iron content of jarosite residue may be utilized to produce theoretically the ferrous materials. The difficulty in production of high quality poly-ferric sulfate （PFS） is how to remove impurities contained in jarosite residue. This paper proposes a novel method for disposing sodium-jarosite which can be used to synthesize PFS, a very important reagent for treating waste water. The method consists of a two-step leaching experimental procedures. The first step, pre-leaching process, is to remove impurity metals by strictly controlling the leaching conditions. The acid concentration of acidic water was adjusted according to the content of impurity metals in sodium-jarosite and the leaching temperature was controlled at 25°C. The second step is to decompose sodium-jarosite to provide enough ferric ions for synthesizing PFS, the concentrated sulfuric acid consumption was 0.8 mL·g^-1 sodium-jarosite and the leaching temperature was above 60°C. In the experiment, decomposing iron from sulfate sodium-jarosite can take the place of ferric martials for synthesizing PFS. Results show that the PFS synthesized from sodium-jarosite had a high poly-iron complex Fe4.67（SO4）6（OH）2·20H2O. Further, the PFS product’s specifications satisfied the national standard of China.

An enhanced coagulation using ferric chloride and poly-ferric chloride coagulant assisted by polyamidine:Performance and mechanisms

The deterioration of water caused by industrial production is a thorny problem.Solving the problem cogently through innovative coagulationstrategies has been recognized of important practical significance.In this work,a simple enhanced coagulation by using ferric chloride(FC)and poly-ferric chloride(PFC)coupled with polyamidine(PA)were tried to remove the toxic organics.The results shown that PA addition could obviously enhance coagulation performances of the iron-based coagulants.The synergic coagulation process and mechanism were studied and discussed in detail based on the coagulation behaviors,flocs properties,removal eficiency and zeta potentials.FC and PFC remove organics mainly through charge neutralization and adsorption-bridging,resulting in a good purification performance.While PA with a higher charge density showed better purification performance due to enhanced charge neutralization.It is worth mentioning that the addition of PA could make the coagulants adapt to a wider pH range,and remove the toxic organics more effectively.That is to say,the practical adaptability of the coagulant was enhanced.This work thus provides a simple strategy to effectively purify wastewater and further improve the water safety.