Yong Kang

Evaluation of storage methods for the conversion of corn stover biomass to sugars based on steam explosion pretreatment

Effects of dry and wet storage methods without or with shredding on the conversion of corn stover biomass were investigated using steam explosion pretreatment and enzymatic hydrolysis. Sugar conversions and yields for wet stored biomass were obviously higher than those for dry stored biomass. Shredding reduced sugar conversions compared with non-shredding, but increased sugar yields. Glucan conversion and glucose yield for non-shredded wet stored biomass reached 91.5% and 87.6% after 3-month storage, respectively. Data of micro-structure and crystallinity of biomass indicated that corn stover biomass maintained the flexible and porous structure after wet storage, and hence led to the high permeability of corn stover biomass and the high efficiency of pretreatment and hydrolysis. Therefore, the wet storage methods would be desirable for the conversion of corn stover biomass to fermentable sugars based on steam explosion pretreatment and enzymatic hydrolysis.

Treatment of acid mine drainage by sulfate reducing bacteria with iron in bench scale runs

In order to treat acid mine drainage (AMD) effectively using sulfate-reducing bacteria (SRB) at high concentration of sulfate and heavy metals, Fe(0) was added to enhance the activity of SRB. When AMD was treated by SRB and Fe(0) at 25 °C, more than 61% of sulfate was removed and the effluent pH was improved from 2.75 to 6.20 during the operation. Cu(2+) was removed effectively with the removal efficiency at 99%, while only 86% of Fe(2+) was removed during the AMD treatment, without conspicuous change of Mn(2+) in the effluent in the process.

Recycled aqueous ammonia expansion (RAAE) pretreatment to improve enzymatic digestibility of corn stalks

A novel lignocellulose pretreatment method using aqueous ammonia for biofuel production was proposed in this study, which named recycled aqueous ammonia expansion (RAAE). Effects of temperature, pretreatment time, water to dry corn stalks loading and flow rate of aqueous ammonia on substrate enzymatic digestibility and sugar yield were investigated. Pretreatment temperature and time are important factors that affect RAAE process. Recirculation process could improve biomass digestibility and sugar yield compared with batch experiment. After RAAE pretreatment, about 70% of the lignin was removed, while more than 90% of the cellulose was preserved in the solids, the substrate crystallinity also increased because of the removal of amorphous portion. The maximum glucan enzymatic digestibility of pretreated biomass was 85.70%, which was obtained at 85°C, 11 min, 80% water to dry corn stalks loading and 1.5L/min aqueous ammonia flow rate.

Effects of microwave power and microwave irradiation time on pretreatment efficiency and characteristics of corn stover using combination of steam explosion and microwave irradiation (SE-MI) pretreatment.

The effects of microwave power and microwave irradiation time on pretreatment efficiency and characteristics of corn stover were investigated based on a new process named combination of steam explosion and microwave irradiation (SE-MI) pretreatment. Results showed that with microwave power and microwave irradiation time increasing, glucose and xylose that released into hydrolyzate, as well as enzymatic hydrolysis yields and sugar yields of glucose and xylose were all slightly increased after SE-MI pretreatment. The maximum sugar yield was 72.1 g per 100 g glucose and xylose in feedstock, achieved at 540 W microwave power and 5 min microwave irradiation time. XRD analysis showed that the crystallinity of biomass was 15.6-19.9% lower for SE-MI pretreatment with microwave effect than that without microwave effect. However, low microwave power and short microwave irradiation time were favorable for SE-MI pretreatment considering energy consumption.