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4 Things to Know about Energy Efficient Wastewater Treatment

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Wastewater treatment is a necessity in today’s world where natural resources are rapidly
getting depleted. Water is essential for life to thrive and lack of access to clean and fresh
drinking water in regions can lead to disease-prone, undernourished and disadvantaged
populations.

North America has one of the most efficient wastewater management systems in the world.
Even though 76% of wastewater is treated, only about 4% of that is reused. There are several
ways in which treated wastewater can be reused. It can also be a source of bio-energy and can
effectively reduce the energy costs of treatment.

Here are a few ways in which waste water treatment can optimize the results and offset
expenses incurred during the process.

1. Treatment and Reuse Are Two Sides of the Same Coin
Treatment without reuse is wastage of a valuable resource. Municipality water that is
scientifically treated can be reused for agricultural purposes, groundwater replenishment and
industrial needs. It is also possible to treat wastewater and make it suitable for drinking, but
then we as a community will have to get past the ‘ick factor’ associated with toilet-to- tap
recycling concept.

Government policy and regulations are very much required if water conservation, treatment
and reuse have to be implemented effectively. Increased water tariffs, strong conservation
efforts and detailed reuse policies are the need of the hour.

2. Use of Latest Technology Aids Efforts
Latest and cutting edge technology makes water management processes easy and cost
effective.

Nanotechnology in filtration allows to remove microbes, bacteria and other minute particles
and provides safe drinking water. Nanotechnology uses nanoparticles to remove microbes. The
nanoparticles release silver ions that destroy the bacteria and other bio matter, and gives safe
drinking water.

Membrane technology uses ceramic membranes whose pores are only 10-20 nanometers
across to desalinate and purify water. The technology also has found popularity due to it being
cost effective and suitable for large scale implementation.

Seawater desalination is another technique that allows countries with little to no availability of
freshwater to convert seawater to drinking water. But the technology is very expensive with
reverse osmosis being a very energy-intensive process. Other alternatives being explored
include biomimicry where the biological osmosis being carried out by mangroves and
euryhaline fish are attempted to purify water. Biomimetic membranes also allow water to be
effectively shuttled through them while trapping the salts.

Waste water management becomes cost effective when nutrients are removed from the sludge
to make fertilizers or when biogas is extracted from the treatment process.

3. Harnessing Water for Energy
Wastewater treatment can be optimized for energy production. The municipal wastewater has
potentially about three times more energy in it, than is required to treat it. If utilities and waste
water management sites are able to harness this energy trapped in the wastewater, then that
will revolutionize the entire cycle of wastewater management.

Anaerobic digesters help convert wastewater to renewable energy by harnessing biogas from
the sludge. Methane can be used to meet the energy requirements of the treatment plant thus
bringing down the overall costs. The biogas can be used for cogeneration and other heating
requirements in the plant. Flaming of the excess gas will result in wastage of useful methane
gas in plants.

Cogeneration or combined heat and power (CHP) is an efficient and clean method of producing
both power and heat energy from a single fuel source. In anaerobic digesters methane is
produced when biosolids are digested. A CHP system will ensure that methane is harnessed to
produce power and thereby increases operational efficiency and reduces energy costs.
Energy management in wastewater treatment plants can be made energy efficient through
solids handling and removal as well. Dewatering sludge can reduce waste handling costs. Sludge
can also be used as biofuel for cogeneration of power. San Diego and San Francisco Bay Area
are leading in biosolids management and applications.

Dissolved Oxygen (DO) needs to be monitored continuously. The DO sensors with suitably sized
blowers will help measure, monitor and control the aeration system. Pump and blower
optimization helps increase energy efficiency. Using the right pumps and blowers at the right
time is extremely important.

Equalization basins also help in improving plant energy efficiency.

4. Use of Heat Flow Meters
The digester is simply a huge vessel in which sludge is treated leading to breakdown of organic
material. Consequently biogases are released as byproducts. With minimization of flaring or
burning of gases, proper utilization of the biogas is possible.

It is necessary to measure biogas concentrations in the digester accurately to understand gas
usage and engine efficiency. Accurate heat flow meters will be able to measure changing biogas
concentration from an anaerobic digester to an internal combustion engine. Drastic fluctuations
in meter readings can signal premature wear of machinery or other problems. Heat flow meters
help monitor the entire CHP and ensure its smooth operation. Flaring converts methane into
CO2 and releases it into the atmosphere. By installing CHP systems, treatment plants are also
able to reduce greenhouse emissions and make a positive impact on the environment.

Conclusion
Judicious and careful use of all natural resources is a prerequisite for the survival of the human
race. Optimal wastewater management will ensure that we have access to safe water supply
irrespective of climatic conditions or other environmental factors. The right use of technology
will help make wastewater treatment energy efficient and sustainable.

 

Ann Neal is a freelance writer who covers technology and business. She is passionate about music and loves to play guitar in her free time with her cute pooch listening quietly 😉

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