Anaerobic reactors with biofilter and different diameter-length ratios in cassava starch industry wastewater treatment

The use of anaerobic reactors with media support in the treatment of wastewater from the cassava starch industry has emerged as a viable option because it allows the application of high organic loads and a significant reduction of the HDT needed for the treatment. This research aimed at studying the process of biodigestion in two anaerobic reactors with bamboo support, in the treatment of effluent of cassava starch, by evaluating their performance. The two reactors used present the following diameter: length ratio, 1:6 and 1:3. The organic loads applied to the systems were 0.519, 1.156, 1.471, 3.049, 4.347, 4.708 and 5.601g.L-1.d-1. Regarding the efficiency of removal of COD, TS and TVS, no statistically significant differences were obtained between the reactors. The two systems evaluated showed a stable behavior with respect to the VA/TA (volatile acidity/total alkalinity) for all submitted loads. The reactors tended to the maintenance of biogas production as a function of consumed COD for the last three organic loads applied, indicating an ability to withstand higher organic loads.

Preparation of solid composite polyferric sulfate and its flocculation behavior for wastewater containing high concentration organic compounds

A new kind of inorganic polymer flocculant, the solid composite polyferric sulfate (SPFS) was prepared using ferrous sulfate and Na-Bentonite. The obtained SPFS was characterized by FT-IR spectra, thermogravimetric analysis (TG), scanning electron microscope (SEM) and X-ray Diffraction (XRD). It showed that SPFS was a kind of composite inorganic polymer, which was the complex of PFS and Na-Bent, not only a simple mixture of raw materials. The synthetic mechanism and surface structure of SPFS were also discussed. Acting as a kind of environment-friendly flocculating agent, the solid composite polyferric sulfate (SPFS) was applied in pretreatment of potato starch industry wastewater, a typical wastewater containing high concentration organic compounds, which COD was above 6,000 mg/L. The results showed that the COD removal value reached 4,070 mg/L with COD removal rates being 46.6%. Based on these results, it is suggested that the SPFS can be attractive pretreatment agent for the starch industry wastewater.