Anaerobic digestion (AD) for biogas production leads to several changes in the composition of the resulting digestates compared to the original feedstock (ammonia content, pH, carbon to nitrogen ratio, etc.), which are relevant for the plant availability of macro- and micronutrients after field application. Increased NH4+-N content in digested slurries compared to undigested slurries does not guarantee improved uptake efficiency of slurry nitrogen and increased savings in fertilizer nitrogen. AD of crop residues and cover crops leads to an increase in the total amounts of mobile organic manures within the farming system, resulting in a higher nitrogen use efficiency and an increased scope for target-oriented nitrogen application in time and space, when needed by the crop, as an alternative to the site-bound soil incorporation as green manures. AD of dairy manure appears to reduce the fraction of immediate plant available phosphorus and micronutrients. This does, however, not affect short-term crop availability under field conditions. More studies are needed to improve current knowledge on sulfur losses during AD and fertilizer value of digestates.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/elsc.201100085

Effects of anaerobic digestion on digestate nutrient availability and crop growth: A review

Sorption behavior and mechanism of hydrophilic organic chemicals to virgin and aged microplastics in freshwater and seawater.

Realistic wave generation and active wave absorption for Navier–Stokes models: Application to OpenFOAM®

Water purification for human use, ecosystem management, agriculture, and industry is emerging as a leading global priority. Access to sufficient clean water ultimately requires improvements over the current state of water filtration technology. Membrane technologies for water purification have been actively pursued for decades, but with recent innovation of both analytical and fabrication tools, more advanced membrane technologies are surfacing. Here, we review the design, development, and application of new membrane materials, fabrication methods for controlling the filtration size regime, analytical tools for performance testing, and molecular modeling for transport and separation. Membrane chemical stability, fouling, and environmental impact as open questions are also presented.

Membrane materials for water purification: design, development, and application

A review of polymeric membranes and processes for potable water reuse

Marinated herring processing brines, which are usually discarded, are rich in salt, protein, non-protein nitrogen, iron, fatty acids, antioxidant and even possess enzymatic activity. This study investigated the performance of ceramic ultrafiltration of two herring spice brines with a major focus on recovery of high value biomolecules such as proteins, fatty acids, minerals, and phenolic compounds. Chemical and biological oxygen demand (COD, BOD5) as well as total suspended solids (TSS) were also measured to follow the performance of the ultrafiltration. The retentates contained 75–82% ( 95% TSS and >85% iron was obtained using the ceramic membranes. The two permeates generated were both fat-free and contained approx. 2% of the proteins compared to the unfiltered brines, and the retention of the phenolic compounds were ranged from 0 to 39%. The results presented in this work demonstrate that ceramic ultrafiltration can recover biomolecules from marinated herring brines although pre-filtration optimization is still needed.

Recovery of biomolecules from marinated herring (Clupea harengus) brine using ultrafiltration through ceramic membranes

The zwitterionic homopolymer poly[2-(methacryloyloxy)ethyl-dimethyl-(3-sulfopropyl) ammonium hydroxide was coated onto the surface of commercial polyamide reverse osmosis (RO) membranes. Aqueous solutions of the polymer at different concentrations were applied to modify the polyamide membranes through an in situ surface coating procedure. After membrane modification, cross-flow filtration testing was used to test the antifouling potential of the modified membranes. The obtained data were compared with experimental data for unmodified membranes. Each test was done by cross-flow filtering tap water for 60 hours. Yeast extract was added as a nutrient source for the naturally occurring bacteria in tap water, to accelerate bacteria growth. Fourier transform infrared spectroscopy, contact angle, scanning electron microscopy, atomic force microscopy, and permeation tests were employed to characterize membrane properties. The results confirmed that modifying the membranes enhanced their antifouling properties and cleaning efficiency, the fouling resistance to bacteria improving due to the increased hydrophilicity of the membrane surface after coating. In addition, the water permeability and salt rejection improved. This in situ surface treatment approach for RO membranes could be very important for modifying membranes in their original module assemblies as it increases water production and reduces the salt content.

Morten Lykkegaard Christensen

Papers

Recovery of biomolecules from marinated herring (Clupea harengus) brine using ultrafiltration through ceramic membranes

Surface modification of reverse osmosis membranes with zwitterionic polymer to reduce biofouling

Forward Osmosis with High-performing TFC Membranes for Concentration of Digester Centrate prior to Phosphorus Recovery

New approach to determining consolidation coefficients using cake-filtration experiments

Direct observation of fouling phenomena during cross-flow filtration