Promoting Resource Efficiency in Small & Medium size ... - UNEP

educe water use by 85%). Promote the use of condensatereturn
systems for sterilisers.
• Equip all vacuum sterilisers with mechanical vacuum systems.
• Install dry-vacuum systems that do not use water for the pump
seal.
• Check type of fume hoods.
• Check if hood scrubber is equipped with recirculating system.
• Fume hoods should employ dry hood-exhaust systems
wherever possible. Use recirculating systems in hood
scrubbers.
4.4.9 Office
• Identify unnecessary water usage and fix leaks.
• Use minimum amounts of water to accomplish the task.
• Recirculate water within a process or group of processes.
• Reuse water sequentially (e.g. use cascades).
• Treat and reclaim used water.
• Replace potable water supplies with water from non-potable
sources where appropriate.
• Install meters and probes (e.g. conductivity) on waterconsuming
equipment.
• Install pressure-reducing valves.
• Rainwater harvesting is the process of collecting, filtering
and storing water from rooftops, paved and unpaved areas
for multiple uses. The harvested water can also be used for
potable purposes after testing and treatment. The surplus water
after usage can be used for recharging groundwater aquifer
through artificial recharge techniques. This can also result in
improving the quality of the groundwater e.g. lower fluoride
content in groundwater. Rainwater harvesting mechanisms are
designed after assessing the site conditions such as incident
rainfall, subsurface strata and their storage characteristics,
infiltration tests and by building suitable structures to collect
and store rainwater.
• A rainwater harvesting system provides a source of soft, highquality
water, reduces dependence on wells and other water
sources and in many contexts is cost effective. A rainwater
harvesting system can range in size from a simple PVC tank to
a contractor-designed and built sump. Rainwater systems are
inherently simple in form.
4.4.10 Water for cleaning and rinsing
• Sub-metering and monitoring allows excessive water
consumption and leaks to be quickly detected and corrected.
• Use low-flow ‘fogging’ nozzles to rinse parts efficiently.
• Use flow restrictors in water lines that supply hoses and
pressure washers.
• Use timers to shut off process water rinses when process is
shut down.
• Turn off running water when not in use.
• Ensure stationary spray nozzles are aimed properly.
• Review nozzle spray patterns for optimum application. Fan,
cone, hollow cone, air atomizing, fine spray and fogging are a
few examples of nozzle spray patterns.
• Replace worn spray nozzle heads; they can result in poor spray
patterns and excessive water consumption.
• Use counter current washing techniques.
• Use conductivity controllers to regulate rinse waterflow rates.
• Use spray washing/rinsing techniques for tank cleaning vs.
refilling/dropping tank wash-water.
• Changes in the type, temperature and concentration of
cleaning solutions can save water.
• Overflow controls should be in place for filling tanks and
vessels.
• Cover hot water basins to avoid evaporation losses
4.4.11 Boiler
• Monitor blowdown rates, feed water quality and blowdown
water quality regularly.
• Install an automatic blowdown control that constantly
monitors boiler water conductivity and adjusts the blowdown
rate accordingly to maintain the desired water chemistry. A
probe measures the conductivity and provides feedback to the
controller driving a modulating blowdown valve. An automatic
blowdown control can keep the blowdown rate uniformly
close to the maximum allowable dissolved solids level, while
minimizing blowdown and reducing energy losses. Changing
from manual blowdown control to automatic control can
reduce a boiler’s blowdown water losses by up to 20%.
• Implement or improve condensate return systems.
• Improving external and internal feed water treatment.
4.4.12 Steam system
• Steam lines and traps should be checked for leaks periodically
and repairs should be scheduled.
• Condensate should be recovered as much as possible
4.4.13 Air conditioning
• Consider recycling of air conditioning condensate water. This
is achieved by modifying the existing air conditioning drains
to allow collection of the water and utilise where needed.
4.4.14 Cooling
• Consider replacing water-cooled equipment with air-cooled
equipment.
• Reuse the once-through cooling water for other facility
water requirements such as cooling tower make-up, rinsing,
washing and landscaping.
• For most efficient cooling in cooling towers, the air and water
must mix as completely as possible.
• When the dew point temperature is low, the tower air induction
fans can be slowed by using a motor speed control or merely
cycled on and off, saving both energy and water evaporation
losses.
• Reduction in drift through baffles or drift eliminators will
conserve water, retain water treatment chemicals in the system
and improve operating efficiency.
• Replace or repair damaged baffles or drift eliminators.
• Optimisation of blowdown, in conjunction with proper water
treatment, represents the greatest opportunity for water
efficiency improvement.
• To better control the blowdown and concentration ratio, install
sub-meters on the make-up water feed line and the blowdown
line.
• Minimum blowdown rates must be determined in tandem
with the optimum water-treatment programme (including
controlling of parameters) for the cooling tower as maximum
concentration ratio for proper operation will depend on the
feed water quality (pH, TDS, alkalinity, conductivity, hardness
and micro-organism levels)
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