Applying artificial neural network to predict the viscosity of microalgae slurry in hydrothermal hydrolysis process

Estimation of the viscosity of microalgae slurry is the premise for the design of industrial reactors in microalgal biofuel production.To accurately predict the viscosity of microalgae slurry(Chlorella pyrenoidosa),an artificial neural network(ANN)model is designed in this study.In the ANN model,the mass fraction of microalgal cell,shear rate,temperature,and retention time during the hydrothermal hydrolysis process are used as the input variables,and the viscosity of microalgae slurry is obtained as the output variable.Comparisons show that the ANN model is in excellent agreement with the experimental data.The mean square error(MSE),Mean Absolute Error(MAE),and goodness of fit(R 2)are 0.725,0.484 and 0.991,respectively.The results provide a proof-of-concept for using ANN models to estimate the viscosity of microalgae slurry.In particular,the developed ANN model can accurately predict the viscosity of microalgae slurry in a hydrothermal hydrolysis process,which cannot be accurately predicted by a standard curve fitting method.

Influence of magnesium and aluminum salts on hydrolysis of titanyl sulfate solution

The influence of magnesium and aluminum salts as impurities on the hydrolysis of titanyl sulfate was investigated.The degree of TiOSO4 conversion to hydrated titanium dioxide（HTD） and the particle size of HTD were measured as functions of the concentrations of MgSO4 and Al2（SO4）3 in the TiOSO4 solution.The Boltzmann growth model,which focuses on two main parameters,namely the concentrations of Mg2＋ and Al3＋（ρ（Mg2＋） and ρ（Al3＋）,respectively）,fits the data from the hydrolysis process well with R20.988.The samples were characterized by ICP,SEM,XRD,and laser particle size analyzer.It is found that the addition of Mg SO4 simultaneously improves the hydrolysis ratio and the hydrolysis rate,especially when F（the mass ratio of H2SO4 to TiO2） is high,hydrolysis ratio increases from 42.8% to 83.0%,whereas the addition of Al2（SO4）3 has negligible effect on the chemical kinetics of HTD precipitation during the hydrolysis process,hydrolysis ratio increases from 42.8% to 51.9%.An investigation on the particle size of HTD reveals that the addition of Mg SO4 and Al2（SO4）3 clearly increases the size of the crystallites and decreases the size of the aggregates.

Preparation of hexagonal and amorphous chromium oxyhydroxides by facile hydrolysis of K_xCrO_y

The hydrolysis process and mechanisms of unique as-prepared KCrO2 and K3 CrO4 were systematically investigated. The characterization results of XRD, IR and SEM show that the hydrolysis reaction can be realized at a low reaction temperature of 80 ℃ and a reaction time of 24 h. Moreover, the greyish-green α-CrOOH with a hexagonal plate-like morphology and a large size of 10 μm is formed via the hydrolysis of the single-phase hexagonal KCrO2, while the green sol-gel of amorphous Cr(OH)3 with a lumpy aggregate morphology is generated through the hydrolysis of a cubic K3 CrO4. It is a facile and rapid method to synthesize pure-phase chromium oxyhydroxide via the above hydrolysis.

Elucidating the removal mechanism of N,N-dimethyldithiocarbamate in an anaerobic-anoxic-oxic activated sludge system

N,N-Dimethyldithiocarbamate （DMDTC） is a typical precursor of N-nitrosodimethylamine （NDMA）. Based on separate hydrolysis, sorption and biodegradation studies of DMDTC, a laboratory-scale anaerobic-anoxic-oxic （AAO） system was established to investigate the removal mechanism of DMDTC in this nutrient removal biological treatment system. DMDTC hydrolyzed easily in water solution under either acidic conditions or strong alkaline conditions, and dimethylamine （DMA） was the main hydrolysate. Under anaerobic, anoxic or oxic conditions, DMDTC was biodegraded and completely mineralized. Furthermore, DMA was the main intermediate in DMDTC biodegradation. In the AAO system, the optimal conditions for both nutrient and DMDTC removal were hydraulic retention time 8 hr, sludge retention time 20 day, mixed-liquor return ratio 3：1 and sludge return ratio 1：1. Under these conditions, the removal efficiency of DMDTC reached 99.5%; the removal efficiencies of chemical organic demand, ammonium nitrogen, total nitrogen and total phosphorus were 90%, 98%, 81% and 93%, respectively. Biodegradation is the dominant mechanism for DMDTC removal in the AAO system, which was elucidated as consisting of two steps： first, DMDTC is transformed to DMA in the anaerobic and anoxic units, and then DMA is mineralized to CO2 and NH3 in the anoxic and oxic units. The mineralization of DMDTC in the biological treatment system can effectively avoid the formation of NDMA during subsequent disinfection processes.