Water Reuse Handbook - the Public Building Commission of Chicago

Water Reuse Handbook
6
Day Tank
18 : Public Building Commission of Chicago
the preferred option for chlorine purification systems. These
diverting 10 gallons for every 1,000
are similar to square what is feet used of for roof large-scale is sufficient. water treatment If drip
facilities but irrigation are more user-friendly is planned, and however, safe for building sediment
maintenance filtration staff (or residents) may be to necessary handle. The to tablets prevent are
clogging of emitters. As standards differ,
combined with water in a hopper to create a liquid chlorine,
the drip irrigation manufacturer or
which is then vendor applied should to the rainwater be contacted to achieve regarding a satisfactory
level. The tablets filtering must of be water. replenished; the frequency depends
on the usage For of the potable system. Use water of briquettes systems, or treatment tablets is
recommended beyond for systems the leaf where screen a full-time and roof maintenance washer staff
is not employed. is necessary to remove sediment and
disease-causing pathogens from stored
water. Treatment generally consists of
Ultraviolet (UV) light: filtration UV light and is an disinfection accepted purification processes alternative in
to chlorine. A specific series wavelength before of UV distribution light destroys to any ensure organisms
present in the rainwater. health Typically, and safety. UV purification consists of a series
of in-line sediment Cartridge filters which Filters filter the and rainwater Ultraviolet to 1 micron (UV) prior
to disinfection by the Light UV light. The rainwater must be filtered prior
to exposure to the UV The because most suspended popular disinfection particles in the array water in can
Texas is two in-line sediment filters –
shield pathogens from disinfection. The UV light should be located
the 5-micron fiber cartridge filter
before the storage followed tank, although by an the additional 3-micron UV light activated may be
placed in the storage charcoal tank to continue cartridge disinfection. filter – followed As an alternative by
to having another UV ultraviolet light in the light. tank, This rainwater disinfection may be recirculated set-up
is placed after the pressure tank or after
past the UV light in order to provide continual disinfection; however,
the on-demand pump.
this may heat the water over time.
It is important to note that cartridge
filters must be replaced regularly.
UV purification systems Otherwise, have maintenance the filters requirements can actually as harbor well. The
UV bulb needs to be bacteria changed and approximately their food once supply. every 10,000 The 5hours
or after 12 months micron of continuous filter use; mechanically some bulbs come removes with an alarm
suspended particles and dust. The 3-
that alerts occupants when the light quality is degrading. In addition,
micron filter mechanically traps
the sediment filters microscopic need to be replaced particles regularly. while smaller
organic molecules are absorbed by the
activated surface. In theory, activated 2
1
2
There are two major charcoal types of tanks can absorb that may objectionable be used within 1
START odors FILTER/ a
RAINWATER START DIVERSION
rainwater harvesting and system, tastes, depending and even on some the design protozoa of the RAINWATER
CATCHMENT -Vortex and
CATCHMENT system
and quantity of water cysts desired (Macomber, to be collected--a 2001). (ROOF) -Solenoid
(ROOF) -First �ush
holding tank and a
day tank. A day tank Filters is smaller can and be meant arrayed to hold in treated parallel rainwater for
greater water flow. In other words, two
until it is needed for flushing.
5-micron fiber filters can be stacked in
one large cartridge followed by two 3-
Sizes of the system’s micron tanks can activated be determined charcoal by several filters factors, in
including the demand for treated water, rainwater supply of the
Tools and Strategies: Rainwater Harvesting System Design
FILTER/
DIVERSION
-Vortex 3
-Solenoid
-First �ush WATER
STORAGE
Holding Tank
18
Figure 2-12. Typical treatment installation of
UV Light (top horizontal cylinder)
an on-demand pump, 5-micron fiber filter, 3micron
Texas Rainwater activated Manual charcoal filter, and an
ultraviolet lamp (top).
another cartridge. The ultraviolet (UV)
light must be rated to accommodate the
increased flow.
NSF International (National Sanitation
Foundation) is an independent testing
and certification organization. Filter
performance can be researched using a
simple search feature by model or
manufacturer on the NSF website. (See
References.) It is best to purchase NSFcertified
equipment. VENTILATION
VENTILATION
Maintenance of the UV light involves
cleaning VENTILATION of the quartz sleeve. MUNICIPAL Many MAKE-UP WATER UV
lights are designed AIR with GAP
AIR GAP an integral
wiper 3 unit. Manual cleaning of the
sleeve WATER is not 4 4recommended
6
due to the 7
STORAGE
possibility FILTER FILTER of breakage. DAY DAY TANK
Holding Tank
OVERFLOW OVERFLOW
UV lamps are rated in gallons DRAIN
DRAIN per
minute. FINISH For single 5-micron 5 and 3micron
Outdoor Use
5
in-line filters, PURIFICATION a UV light rated at
(Irrigation System)
PURIFICATION
12 gallons per minute is sufficient. For
VENTILATION
FINISH
Outdoor Use
(Irrigation System)
MUNICIPAL MAKE-UP WATER
August 2011
7
BOOSTER BOOSTER
PUMP PUMP
8
FINI
Indo