Sequencing Batch Integrated Fixed-Film Activated Sludge Membrane Process for Treatment of Tapioca Processing Wastewater.

Tapioca processing industries are very popular in the rural community to produce a variety of foods as the end products. Due to their small scales and scattered locations, they require robust modular systems to operate at low capacity with minimum supervision. This study explores the application of a novel sequencing batch-integrated fixed-film activated sludge membrane (SB-IFASM) process to treat tapioca processing wastewater for reuse purposes. The SB-IFASM employed a gravity-driven system and utilizes biofilm to enhance biodegradation without requiring membrane cleaning. The SB-IFASM utilizes the biofilm as a secondary biodegradation stage to enhance the permeate quality applicable for reuse. A lab-scale SB-IFASM was developed, preliminarily assessed, and used to treat synthetic tapioca processing industry wastewater. The results of short-term filtration tests showed the significant impact of hydrostatic pressure on membrane compaction and instant cake layer formation. Increasing the pressure from 2.2 to 10 kPa lowered the permeability of clean water and activated sludge from 720 to 425 and from 110 to 50 L/m2·h bar, respectively. The unsteady-state operation of the SB-IFASM showed the prominent role of the bio-cake in removing the organics reaching the permeate quality suitable for reuse. High COD removals of 63-98% demonstrated the prominence contribution of the biofilm in enhancing biological performance and ultimate COD removals of >93% make it very attractive for application in small-scale tapioca processing industries. However, the biological ecosystem was unstable, as shown by foaming that deteriorated permeability and was detrimental to the organic removal. Further developments are still required, particularly to address the biological stability and low permeability.

Preliminary Study on Transformation of Human canstatin Gene to the Novel Bioreactor——Dunaliella salina / 中国生物工程杂志

The human canstatin cDNA was amplified by RT-PCR and then directionally cloned into pU? expression vector. The recombinant pU?-Can vector was connected with the screening marker (bar box), to construct a eukaryotic expression vector called pU?-Can-Bar. This expression vector was introduced into the D.salina by glass beads method. The screening culture of transformants of D.salina was performed in solid media containing 5 ?g/ml PPT, and the analyses of transformants were carried out through PCR and Southern blot. PCR results revealed that specific 700 bp products were detected in the different transformants of D.salina but not in negative control. Southern blot analysis further demonstrated that human canstatin gene was integrated into the D.salina genome. Moreover, the results of genetic stability analyses of transformants demonstrated that canstatin gene was stably inherited in the D.salina transformants. The successful preparation of the D.salina transformants will provide the experimentation evidence for producing canstatin protein cosmically by using the D.salina bioreactor and give a better prophase work basis for clinic application of canstatin protein early.