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Hint
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Answer
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Biological Cycle
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Materials that can biodegrade and be safely returned to the earth
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Technical Cycle
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Relevant for products that are used rather than consumed, focusing on how each step allows materials to remain in use rather than becoming waste
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Biological Cycle methods
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Regeneration
Farming
Composting and anaerobic digestion
Cascading
Extraction of Biochemical feedstocks |
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Regeneration
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Instead of continuously degrading nature, build natural capital. Ensures bioresources are returned to biosphere
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Farming
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Manage farms and other sources of biological resources in ways that create positive outcomes for nature
E.g Improve biodiversity, organic fertilizers |
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Composting and Anaerobic digestion
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From WWTP; biogas, digestate for soil improvement
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Cascading
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Makes use of products and materials for multiple purposes as they degrade in quality from high value to low value applications, before being returned to the biosphere
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Extraction of Biochemical Feedstocks
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Taking both post-harvest and post-consumer biological materials as feedstock. Uses biorefineries to produce low-volume high value chemical products.
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Technical Cycle Methods
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Sharing
Maintaining
Reusing/Redistributing
Refurbish/Remanufacture
Recycling |
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Sharing
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Increases utilisation of products
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Maintaining
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Keeps product in original form, maintains functionality
Diverting products to other customers |
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Refurbish/Remanufacture
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Returns products to good working order; restores value.
When products can't remain in circulation so undergo changes. |
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Recycle
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Transforming products into basic materials and repurposing/ reusing them
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Water Sector - Circular Economy
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Shift WWT to maximise recovery of resources
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Recoverable resources WWT
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Water
Energy - Biogas upgrading
Nitrogen
Phosphorous
Carbon- Cellulose, Biopolymers |
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Water recovery
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Membrane filtration, water suitable for irrigation industry, non-potable urban uses
Tech: Ultrafiltration, Reverse osmosis |
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Energy - Biogas recovery
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Upgrade biogas to almost pure biomethane
Higher value product
Tech: Membrane separation, pressure swing adsorption
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Nitrogen recovery - Ammonia stripping
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Sludge treatment produces ammonia rich stream, usually returned to wwtp, increasing removal burden.
Uses: fertilisers
Tech: HANSA engineering, converts ammonium ions to ammonia using temp and pH
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Phosphorous recovery - Struvite Precipitation
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Struvite ppt can clog pipes; reduce efficiency
Uses: fertilisers
Tech: Ostara Pearl, anaerobic reactor encouraging biomass to release phosphorous.
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Carbon recovery - Cellulose
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Cellulose fibre in ww from toilet paper
Uses: Soil conditioner, biomass fuel,raw material for paper pulp
Tech: Advanced pretreatment of WWTP inlet, fine mesh sieves.
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Carbon recovery - Biopolymers
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Convert carbonaceous matter into PHA (polyhydroxyalkanoate), a fully biodegradable biopolymer
Replacing fossil fuel derived polymers
Uses: Water bottles, bags
Tech: Fermentation of sludge to produce volatile fatty acids, feed to PHA accumulating organisms. Recover from organisms
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Circular Economy Assessment
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Define inflows and outflows: water, carbon, nitrogen and phosphorous balance.
Core Indicators
% recirculation of outflow to biological cycle
% water discharged to quality requirement
Nutrient extraction from water
Recovery rate of nutrients from ww
Value indicators
Represent economic value as well as environmental and societal value
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