Birgir Norddahl

A review of the current state of biodiesel production using enzymatic transesterification

Enzymatic biodiesel production has been investigated intensively, but is presently employed industrially only in a 20,000 tons/year pilot plant in China (Du et al. [2008] Appl Microbiol Technol 79(3):331–337). This review presents a critical analysis of the current status of research in this area and accentuates the main obstacles to the widespread use of enzymes for commercial biodiesel transesterification. Improved results for enzymatic catalysis are seen with respect to increased yield, reaction time and stability, but the performance and price of the enzymes need further advances for them to become attractive industrially for biodiesel production. Critical aspects such as mass transfer limitations, use of solvents and water activity are discussed together with process considerations and evaluation of possible reactor configurations, if industrial production with enzymes is to be carried out. Results of published studies on the productivity of enzymes are also presented and compared to the use of chemical catalysts. Biotechnol. Bioeng. 2009;102: 1298–1315.

Process simulation and economical evaluation of enzymatic biodiesel production plant

Process simulation and economical evaluation of an enzymatic biodiesel production plant has been carried out. Enzymatic biodiesel production from high quality rapeseed oil and methanol has been investigated for solvent free and cosolvent production processes. Several scenarios have been investigated with different production scales (8 and 200 mio. kg biodiesel/year) and enzyme price. The cosolvent production process is found to be most expensive and is not a viable choice, while the solvent free process is viable for the larger scale production of 200 mio. kg biodiesel/year with the current enzyme price. With the suggested enzyme price of the future, both the small and large scale solvent free production proved viable. The product price was estimated to be 0.73-1.49 euro/kg biodiesel with the current enzyme price and 0.05-0.75 euro/kg with the enzyme price of the future for solvent free process.

Ammonium Fertilizers Production from Manure: A Critical Review

Excessive livestock production in small areas poses a risk of nitrogen release to the environment and thus air and water contamination. Recovery of ammonia is necessary to avoid overfertilization, but manure management of untreated slurry is costly and complex. The authors discuss ammonium fertilizer recovery from manure using membrane processes and physicochemical methods including technology and energy assessments. Currently, nanofiltration, reverse osmosis, membrane distillation combined with ultrafiltration, and air stripping are the best choices. The processes rely highly on selection of appropriate pretreatment, as residual particulates will lead to fouling of membranes and stripping towers hence affect the performance greatly.

Systematic approach for synthesis of intensified biodiesel production processes

Abstract Biodiesel production is a very hot topic within research, politics and investments worldwide. To intensify production and improve decision making and production evaluation, a systematic approach to describe biodiesel production processes is needed. The paper presents a systematic approach for process synthesis of biodiesel production and illustrates the importance of the approach by an example of biodiesel production from waste animal fats. The process synthesis method uses a step-by-step approach to construct, improve or evaluate biodiesel production processes.

Microfiltration and ultrafiltration as a post-treatment of biogas plant digestates for producing concentrated fertilizers

AbstractBiogas plant digestate liquid fractions can be concentrated by microfiltration and ultrafiltration. Two types of microfiltration membranes (polysulphone (PS) and surface-modified polyvinylidene fluoride (PVDF)) were used to process digestate liquid fractions, and to assess their applicability in the recovery of particulate phosphorus, compared to an ultrafiltration membrane (polyethersulphone (PES)). Results show that membrane material, operational conditions, and pore diameter influenced the permeate flux pattern during microfiltration. The PS membranes initially had a higher tendency to foul than PVDF membranes. However, during the filtration process, as fouling built up, the permeate flux behavior of the two membranes became very similar. During the concentration of digestate liquid fractions, the microfiltration PS membrane and the ultrafiltration PES membrane achieved the highest phosphorus rejection (80% w/w), suggesting that there was a correlation between the membrane material and both the...

Fouling of a spiral-wound reverse osmosis membrane processing swine wastewater: effect of cleaning procedure on fouling resistance.

ABSTRACT Swine manure is a valuable source of nitrogen, phosphorus and potassium. After solid–liquid separation, the resulting swine wastewater can be concentrated by reverse osmosis (RO) to produce a nitrogen–potassium rich fertilizer. However, swine wastewater has a high fouling potential and an efficient cleaning strategy is required. In this study, a semi-commercial farm scale RO spiral-wound membrane unit was fouled while processing larger volumes of swine wastewater during realistic cyclic operations over a 9-week period. Membrane cleaning was performed daily. Three different cleaning solutions, containing SDS, SDS+EDTA and NaOH were compared. About 99% of the fouling resistance could be removed by rinsing the membrane with water. Flux recoveries (FRs) above 98% were achieved for all the three cleaning solutions after cleaning. No significant differences in FR were found between the cleaning solutions. The NaOH solution thus is a good economical option for cleaning RO spiral-wound membranes fouled with swine wastewater. Soaking the membrane for 3 days in permeate water at the end of each week further improved the FR. Furthermore, a fouling resistance model for predicting the fouling rate, permeate flux decay and cleaning cycle periods based on processing time and swine wastewater conductivity was developed.