Yun-Huin Lin

Degradation of dimethyl-sulfoxide-containing wastewater using airlift bioreactor by polyvinyl-alcohol-immobilized cell beads

Airlift bioreactor containing polyvinyl-alcohol-immobilized cell beads was investigated for its capability of biodegradation of dimethyl sulfoxide (DMSO) in term of sludge characteristics including the strategy of acclimation with sucrose and the protection of microorganism from poisoning of DMSO by PVA cell beads. Media condition with sucrose at 50 mg L(-1) was beneficial to the biodegradation of DMSO in the fresh PVA entrapped-sludge, but became insignificant in the acclimated one as for tolerance of DMSO toxicity. The removal efficiency of DMSO had the highest rate at 1.42-kg DMSO per kilogram of suspended solid per day after series acclimation batches in the oxygen-enriched airlift bioreactor treated with the 1187.4 mg L(-1) of DMSO. Microbial consortium was required for the complete biodegradation of DMSO without any dimethyl sulfide produced. Pseudomonas sp. W1, excreting extracellular monooxygenase identified by indole, was isolated to be one of the most effective DMSO-degrading microorganism in our airlift bioreactor.

Increasing algal biofuel production using Nannocholropsis oculata cultivated with anaerobically and aerobically treated swine wastewater

For mass production of Nannocholropsis oculata, a cheap nutrition source such as swine wastewater is required. The use of a combination of anaerobically/aerobically treated swine wastewater (AnATSW) was compared to artificial 3×f/2 medium in terms of algal growth rate and oil content. For microalgae cultured in 0-50% (v/v) AnATSW, a biomass of 0.94-3.22 g L(-1) was reached in 5 days. For microalgae cultured in 3×f/2 medium with vitamins, the lipid productivity was 0.122 g L(-1) d(-1) although its oil content reached 48.9%. Culturing N. oculata in 0-50% AnATSW resulted in an optimal lipid productivity of 0.035-0.177 g L(-1) d(-1). Only vitamins improved algal production of more oxidatively stable compositions of unsaturated oils. These oils were similar to the chemical structure of rapeseed oil based on analysis of the bis-allylic-position-equivalent value (30.64-46.13) and the iodine value (90.5-117.46). These oils were similar to coal based on the calculated low-heating-value of 17.6-22.9 MJ/kg.

Continuous lipid extraction of microalgae using high-pressure carbon dioxide.

Sequestering carbon, purifying water, and creating biofuel materials using microalgae are of global interest in the R&D field. However, extracting algal oil consumes a high amount of energy, which is an obstacle for the biofuel market. Nontoxic and recyclable high-pressure CO2 extraction processes are being developed by numerous researchers; however, most of these processes use batch operations mixed with a large amount of co-solvent and require improvement. We fabricated a continuous high-pressure CO2 extraction system, evaluating the optimal parameters for the extraction process. The various parameter tests included temperature, pressure, pretreatment methods, ratio, and the species of co-solvent. We integrated the optimal parameters from previous tests, using a 5-d continuous operation. Compared with traditional solvent extraction, a 90.56% extraction yield ratio was achieved using this continuous extraction method. This shows the stable, high extraction yields of this continuous high-pressure CO2 extraction system.

Treatment of acetone waste gases using slurry-phase airlift embedded with polyacrylamide-entrapped cell beads.

Abstract Acetone is the most common chemical used in the Hsinchu Science Park in Taiwan. The three-phase airlift biore-actor was designed to absorb acetone into the 39 L of medium solution and then degraded by 2-L polyacryl-amide (PAA)-entrapped Thiosphaera pantotropha cell beads. The airlift medium was successfully regenerated and circulated for more than 5 months. The elimination capacity of 350-part per million (ppm) acetone at 10 L ∙ min−1 was 258.4 g · m−3hr−1 (160.4 g-C · m−3hr−1) with 100% removal efficiency in Stage II, higher than previously reported biofiltration results. The maximum chemical oxygen demand:nitrogen ratio of 100:2.9 is achieved, and a balanced nutrient state was indicated by the change in redox potential. The pH of the system was maintained at neutral because of the strong buffer agent added to the medium (final buffer intensity, β=1.18 ×10-2 M). The PAA-entrapped cell beads could also provide a good barrier for high salinity gradient environment and the inoculum source to maintain steady operation of the system.

Rapid Harvesting the Microalgae Nannochloropsis oculata with Polyamide from Isolated Bacillus subtilis DYU2

Polyamide produced from Bacillus subtilis DYU2 was found to have excellent flocculating ability. With the addition of 200 mg/L of polyamide and 50 mg/L of polyaluminum chloride (PAC), the optimum temperature for flocculation performance of polyamide was 30℃, giving the highest flocculating activity and rate of 100.0 and 98.0% within 10 minutes, respectively. Analysis with Fourier transform infrared spectrophotometry (FT-IR), nuclear magnetic resonance spectrometry (NMR) and amino acid identification shows that the polyamide biopolymer mainly possesses the structure of poly-glutamic acid (PGA). The average molecular weight of PGA was about (3.12–3.30) × 10^6 Da as determined by gel permeation chromatography. The major components of PGA were total sugars, uronic acids, proteins and polyamides (homopolymer of glutamic acid), accounting for a weight ratio of approximate 15.0, 2.5, 4.5 and 49.0% (w/w), respectively. Moreover, mechanisms describing the flocculation process with PGA were proposed based on the experimental observations.