Membrane Separation of Raw and Anaerobically Digested Pig Manure

Abstract

Manure ought to be controlled and handled environmentally soundly. Volume reduction of surplus manure by reverse osmosis (RO) is a viable and economic option in certain areas where another alternative is to reduce the number of animals. This membrane separation project arose out of an urgent need to re-establish an ecological balance between farming and the natural environment without necessarily having to decrease the number of livestock. The suggested technical solutions should not significantly reduce the standard of living of the farmers. Dewatering of manure makes it easier to store and transport the nutrients. RO coupled to anaerobic digestion as pretreatment with inherent production of biogas energy leads to on-site production and use of biological fertilizer and humus. Such treatment will improve the hygienic conditions and general health of the farming communities compared to purchase and sole use of chemical fertilizers. Mechanical dewatering of raw as well as anaerobically digested pig manure yields a cake of 25 % solids and a liquid fraction containing 1 % solids. The solid cake contained virtually all the phosphorous, whereas nitrogen was dissolved equally in water in both fractions. A tubular RO membrane plant separated 95 % of the total nitrogen in the liquid fraction. The particle free permeate met the effluent criteria for direct discharge to the neighbouring fjord. The concentrate approached one tenth of the original manure volume and is considered a liquid fertilizer. Cleaning of the membranes was performed with nitric acid and the alkaline detergent Ultrasil 11. The membrane flux was fully recovered after each chemical cleaning.

Beyond land application: Emerging technologies for the treatment and reuse of anaerobically digested agricultural and food waste

“…3). For example, Bilstad et al (1992) used RO for nitrogen recovery from digested manure. The process removed 95% of input total nitrogen, which was retained in the liquid fraction (concentrate), and was therefore considered a viable liquid fertilizer (Bilstad et al, 1992).…”

“…For example, Bilstad et al (1992) used RO for nitrogen recovery from digested manure. The process removed 95% of input total nitrogen, which was retained in the liquid fraction (concentrate), and was therefore considered a viable liquid fertilizer (Bilstad et al, 1992). Additionally RO is effective at high initial TAN concentrations, as demonstrated by Masse et al (2008) who achieved >99% NH 4 + retention efficiency using AD effluent with high initial TAN levels (10,000 mg L À1 ).…”

Decoupling the retention time of easily degradable and persistent substances using ultrafiltration membranes increases biogas production yield

“…Membranes are used to treat wastewater and slurry by livestock farming, reduce volume of surplus manure, and produce a concentrated fertilizer [27][28][29][30][31][32][33].…”

“…Nowadays, in the agricultural industry, all kinds of membrane processes (microfiltration, ultrafiltration, nanofiltration, and reverse osmose) are implemented . Membranes are used to treat wastewater and slurry by livestock farming, reduce volume of surplus manure, and produce a concentrated fertilizer .…”

Fate of Macronutrients in Water Treatment of Digestate Using Vibrating Reversed Osmosis

“…In short-term studies, clean water flux could always be recovered following intensive acidic and alkaline cleaning (Bilstad et al 1992). Atkinson (2005) and Johnson et al (2004), from New Logic Research, reported on the use of Vibrating Shear Enhanced Processing (VSEP) for manure purification.…”