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− | <sup> | + | <sup>1</sup>Georgia DCA, 2009 |
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− | <sup> | + | <sup>2</sup>Met Council, 2011 |
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− | <sup> | + | <sup>2a</sup>Before activated charcoal (if included). |
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+ | <sup>2b</sup>After activated charcoal (if included). Refer to specific UV and carbon filter manufacturer for guidance | ||
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+ | <sup>3</sup> VA Rainwater Harvesting Manual, Cabell Brand center, 2009 | ||
Treatment Method | Primary Purpose | Location in System |
---|---|---|
Pre-storage and in-storage treatment | ||
Filtration/Biofiltration | Reduce particulates and nutrients | Before storage |
Grassed Swale | Reduce particulates | Before sedimentation |
Leaf Screens and Strainers1 | Remove organic solids | Gutters and downspouts (before sedimentation) |
Vortex Filters | Remove organic and gross solids, particulates and debris down to 280 microns. | Before storage and connected to smoothing inlet in tank. |
Screens | Reduce gross solids | Before sedimentation |
Settling Basin/Sedimentation1 | Remove particulates | Before or during storage |
Smoothing Inlet | Prevents the resuspension of settled solids and introduces oxygen to the tank to enhance aerobic conditions | In tank |
Floating Filter | Filter particulates before water enters a submersible pump (protects pump) | In tank |
Skimming Overflow Siphon and Trap | Remove floating debris, (e.g. pollen) and creates a water trap to prevent animals and downstream odors from entering the tank. | In tank |
Aeration Unit | Used to introduce oxygen to tank which aids in the formation of aerobic beneficial bacteria that have been shown to reduce nutrient and metals concentrations. | In tank or can be set up in a venture injection application. |
Post-storage treatment | ||
Activated Charcoal1 | Remove chlorine, reduce odor, remove organics | After sediment filtration, before use and before or after UV filter |
Boiling/distilling1 | Kill microorganisms | Before use |
Chemical treatments (chlorine) 1 | Kill microorganisms | During storage or at distribution. Most commonly injected post filtration at point of distribution or in day tank. Should not be required in tank if adequate prefiltration is implemented |
Electrodialysis2 | Remove dissolved ions (salts) | Between storage and end use
Not required in rainwater systems |
In-line filters | Removes sediment, reduces turbidity, increases ultraviolet treatment | Between storage and end use and prior to UV treatment. Recommend 1 micron to meet current indoor water quality criteria of less than 1 ntu or sample the water and send to the UV manufacturer. |
Microfiltration2 | Remove suspended solids and microorganisms | Between storage and end use |
Ultrafiltration | Remove suspended solids,organics | Between storage and end use |
Nano-filtration2 | Remove multivalent ions, organics microorganisms, viruses and proteins | Between storage and end use |
Reverse Osmosis2 | Remove monovalent ions, organics, microorganisms and viruses. May remove beneficial nutrients and produce highly corrosive water that needs to be reconditioned. | Between storage and end use |
Sand filtration | Between storage and end use | |
Ozonizationb | Inactivate microorganisms | Before use typically applied through a venture and injected into the tank or a smaller contact tank. |
Ultraviolet Disinfectionb | Inactivate microorganisms | Before use |
1Georgia DCA, 2009
2Met Council, 2011
2aBefore activated charcoal (if included).
2bAfter activated charcoal (if included). Refer to specific UV and carbon filter manufacturer for guidance
3 VA Rainwater Harvesting Manual, Cabell Brand center, 2009