Each lid had a screw opening for a stirrer, which gently stirred the water continuously to provide mixing of substrates, and a screw cap-opening with a septum.
Best results were achieved when the pretreatment was carried out at 180 °C for 45 min with mixing of substrate at 100 rpm.
The temperature of the reaction was maintained at 35°C and impeller speed was 200 rpm for proper mixing of substrate and resting cells.
Both digesters are connected together by using three overflows and can thus be operated as one tank due to the mixing of substrate by level adjustment during the feeding.
Substrate was loaded by gentle mixing of substrate and resin in buffer on an end-over-end rotator for 2 h at 30 °C and 30 rpm (0.5 mL).
Although mixing of substrate and enzymes is crucial for an efficient liquefaction, our previous findings showed that it does not appear that lack of mixing is the cause of the decreasing conversion, at least not at the solids levels documented [ 4].
The information available in the database will be useful for the design and operation of anaerobic digesters: Optimization of the mix of co-substrates, choice of the applied OLR, simulation of methane production and of the rate of substrate degradation.
One was a 2X mix of DNA substrate, PPi and enzyme prepared in the reaction buffer (17 mM Tris-HCl (pH 7.5), 17 mM NaCl, 1 mM dithiothreitol and 20% glycerol) along with different sodium pyrophosphate concentrations and was loaded in one syringe.
Activity on CarboxyMethyl Cellulose (CMC, medium viscosity, Sigma-Aldrich) was performed by mixing 4 mL of substrate solution at 10 g/L in 50 mM potassium phosphate buffer pH 6.0, 1 mM CaCl2, 0.01% (w/v) NaN3 with 40 µL of an appropriate enzyme dilution, at 37°C.
