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.