Technology Type - Clean Water Membrane Systems
Technology Strengths,Weaknesses and Critical Indicators
Clean Water Membrane Systems can be used to reduce both suspended and dissolved solids depending on location specific requirements:
- Can produce recycled dischargeable water (RO) and marketable products when paired with other technologies
- Always produces two streams leaving system a stream retained and a stream that permeates the membrane.
- Membranes of various size are often used together to get to clean water: microfiltration or ultrafiltration membranes first followed by reverse osmosis membranes—each allowing various sized particles through the membrane
- Reverse Osmosis membranes are required to remove salts and achieve water suitable for discharge
- Depending on the membrane, effective pre-treatment to remove coarse, fibrous solids as well as fine suspended solids are important to system viability and reliability
- Membrane failure and high pressure/energy costs can be a concern
- Proven technology for nitrogen recovery, phosphorous recovery, and storage reduction
- Dairies desiring significant reduction in volume of manure requiring storage and application.
- Dairies under unique constraints related to storage capacity, lagoon construction/cost, and/or manure hauling to distant fields.
- The technology is available at any scale.
- Both raw and digested manure can be treated but significant pre-treatment of those manures is required.
- Technology is applicable to all climate conditions.
Economic/Return on Investment Considerations
- Capital costs are a concern with installed costs on the high end.
- Operating costs are high, with systems incurring high electrical and chemical costs.
- Significant offset of manure management costs. From 40-70% of pre-treated liquid volume can be converted to ‘clean water’ not requiring storage and application.
- Although markets are not mature, and several factors impact its viability, the concentrate resulting from the removal of water, can be sold for value.
- As of 2018, the number of U.S. installations is around one dozen, mostly at dairies of a smaller size.
- An analysis of locations shows the adoption of the technology to dairies with unique costs related to liquid storage/application.
- The state of the technology in the U.S. is emerging. Presently, significant concerns exist relating to operational uptime, reliability, and true operational costs.
- Multiple vendors and configurations exist, with systems using varying types, forms and sequences of membranes.
- Storage volume reduction, 40-70% of incoming liquid resulting in ‘clean water’ suitable for either discharge, use as process water or animal drinking water—pending meeting local and federal regulations.
- Nutrients partitioned into a concentrated liquid product.
- Produces a concentrate containing all the incoming nutrients/salts.
- Negligible impact on odor is seen with this technology.
- Produced concentrate can have bacteria/virus partitioned into smaller volumes, although the pathogens are not destroyed.
- GHG mitigation is negligible as the initial organics remain in the concentrated form.
- Offsets to existing manure management, specifically lagoon storage maintenance/construction and liquid transportation.
- ‘Clean water’ produced by system can potentially be used as process water, animal drinking water, and new water rights upon discharge to streams—all of which can produce limited offsets and/or revenues, with proper permitting.
- Produced concentrate could be certified organic, producing a value-added liquid fertilizer concentrate for the organic market.
How it works
- Pre-treated manure, with suspended solids removed, are passed through a sequence of membranes using high-pressure pumps. As the liquid enters the membranes, certain nutrients/salts/pathogens are rejected by the size of the membrane while water and other species pass through.
- The rejected material becomes the liquid concentrate while the pass-through becomes the ‘clean water’
- The end products of the process are the liquid concentrate containing the bulk of influent nutrients/salts and a ‘clean water’ with potential for discharge, use as process water, and/or animal drinking water, pending permitting.
Pretreatment and/or Post-treatment Required
- Effective pretreatment is essential. For protection of the membranes, manure must be removed of nearly all suspended solids.
- The liquid concentrate will require storage/application while the ‘clean water’ will need to meet permitting requirements for desired end-use. In the case of discharge to U.S. waterways, a particularly intensive permitting process, the post-treatment might require additional treatments such as ion exchange, activated carbon, oxygenation, outflow processing, etc.
- Key limitations of the technology center on both the high cost and on-going concerns with reliability.
- No renewable energy is produced in this system and considerable electrical energy is required.
- No thermal renewable energy is produced in the system.
- Successful projects require a correct matching of technology with specific volume reduction and corresponding reduction in transportation costs.
- Correct choice of system and operations/maintenance are required to overcome historic reliability and performance concerns.
- Creative use can decrease costs, such as operating the system only during the winter months of required storage or only treating a fraction of manure.
Skilled operations/maintenance, either internal with training or external with professional services, are required for sustained and reliable operation
Budaj, J. S. (2016). Use of reverse osmosis to recover water from a nutrient separation system for dairy manure management. M.S. thesis, Michigan State Univ., East Lansing, MI.
Chiumenti, A., F. da Borso, F. Teri, R. Chiumenti, and B. Piaia. 2013a. Full-scale membrane filtration system for the treatment of digestate from a co-digestion plant. Applied Engineering in Agriculture, 29(6), pp.985-990.
Drosg, B., W. Fuchs, T. Al Seadi, M. Madsen, B. Linke. 2015. Nutrient recovery by biogas digestate processing, IEA Bioenergy, Implementing Agreement for a Programme of Research, Development and Demonstration on Bioenergy, ISBN 978-910154-16-8.
Frear, C., Ma, J., Yorgey, G., (2018). Approaches to nutrient recovery from digested dairy manure. Washington State University Extension, Pullman WA. EM112E.
Pauls, Carlie (2014). Assessment of LWR’s manure treatment system with in-sequence separation and membrane filtration of liquid hog manure. Report by Hylife Ltd. Regarding performance at their hog facility. May 6, 2014.
Wong, K., Xagoraraki, I.,Wallace, J., Bickert,W., Srinivasan, S., and Rose, J. B. (2009). Removal of viruses and indicators by anaerobic membrane bioreactor treating animal waste. J. Environ. Quality, 38(4), 1694–1699.
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