Hualiang Li

Production of a novel bioflocculant by Bacillus licheniformis X14 and its application to low temperature drinking water treatment.

A novel bioflocculant ZS-7 produced by Bacillus licheniformis X14 was investigated with regard to its synthesis and application to low temperature drinking water treatment. The effects of culture conditions including pH, carbon source, nitrogen source, temperature, inoculum size and shaking speed on ZS-7 production were studied. The purified bioflocculant was identified as a glycoprotein consisting of polysaccharide (91.5%, w/w) and protein (8.4%, w/w), with an approximate molecular weight of 6.89 x 10(4)Da. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) indicated the presence of amino, amide, carboxyl, methoxyl and hydroxyl groups. This bioflocculant showed good flocculating performance and industrial potential for treatment of low temperature drinking water, and the maximum removal efficiencies of COD(Mn) and turbidity were 61.2% and 95.6%, respectively, which were better than conventional chemical flocculants. Charge neutralization and bridging were proposed as the reasons for the enhanced performance based upon the experimental observations.

Physical and Chemical Properties of Waste-Activated Sludge After Microwave Treatment

In this study, we investigate the physical and chemical properties of waste-activated sludge after treatment with microwave irradiation. The results indicate that microwave energy and contact time strongly influence the physical and chemical properties of sludge. According to the settling velocity and particle size measurements, the microwave energy of 900 W with a contact time of 60s may be the optimal condition for improving the ability of the sludge to settle. Results of the experiments have shown that supernatant turbidity, soluble chemical oxygen demand, volatile suspended solid solubilization, extracellular polymeric substances content, and inorganic nitrogen increase significantly with contact time. Based on these results, we find that the microwave irradiation treatment specified by the contact time not only improves settleability, but also disintegrates sludge and destroys microbial cells. Possible mechanisms of microwave treatment are also discussed.

Removal of dimethyl sulfide by the combination of non-thermal plasma and biological process ☆

A bench scale system integrated with a non-thermal plasma (NTP) and a biotricking filtration (BTF) unit for the treatment of gases containing dimethyl sulfide (DMS) was investigated. DMS removal efficiency in the integrated system was up to 96%. Bacterial communities in the BTF were assessed by PCR-DGGE, which play the dominant role in the biological processes of metabolism, sulfur oxidation, sulfate-reducing and carbon oxidation. The addition of ozone from NTP made microbial community in BTF more complicated and active for DMS removal. The NTP oxidize DMS to simple compounds such as methanol and carbonyl sulfide; the intermediate organic products and DMS are further oxidized to sulfate, carbon dioxide, water vapors by biological degradation. These results show that NTP-BTF is achievable and open new possibilities for applying the integrated with NTP and BTF to odour gas treatment.

Application of magnetic enhanced bio-effect on nitrification: a comparative study of magnetic and non-magnetic carriers.

A novel magnetic carrier with surface magnetic field of 4 mT was developed for studying the magnetic enhanced bio-effect on nitrification. The bio-effect on nitrificaton induced by the magnetic carrier was studied by comparing the performance of sequencing batch biofilm reactors filled with magnetic (MC) and non-magnetic (NMC) carriers. The result showed that the bioreactor with MC had better performance for nitrification than bioreactor with NMC. During the biofilm culturing period, the time required for nitrification formation in biofilm of the MC reactor was 25% less than that for the NMC reactor. The results also showed that the ammonium oxidation rate of the MC reactor was 1.6-fold faster than that in the NMC reactor at high influent NH4-N concentration, while nitrite oxidation rate was always accelerated regardless of influent NH4-N concentration. The specific oxygen uptake rate analysis revealed that ammonia and nitrite oxidation activities in biofilm of the MC reactor were 1.65 and 1.98 times greater than those of the NMC reactor, respectively.