Water Pollution – At a Glance
Every day, about 2 million tons of sewage, industrial and agricultural waste are discharged into water bodies – this is equivalent to the weight of the entire human population!
Over 80% of wastewater (including 70% of industrial wastes ) is discharged into water bodies largely untreated.
2.1 billion people lack access to safely managed drinking water services.
Water and sanitation related economic losses in Africa could amount to 5% of GDP.
Surface and ground water resources around the world are facing increasing threats of pollution from wastewater from domestic sources and industrial effluents as well as solid waste that changes the chemical and biological properties of water to make them problematic from a human and ecosystem health perspective. This is due to effluents from domestic and industrial point sources as well as non-point sources such as agricultural runoff (e.g. nitrates in groundwater from fertilizers) that results in impacts to people and ecosystems.
Wastewater is used water that comes from human excreta, food waste, soaps, chemicals, oils that occur from showers, toilets, sinks, washing machines, and dishwater, etc. Wastewater has a high level of pollution, which is much greater than natures' ability to attenuate pollution. The lack of wastewater treatment estimated at 80 percent globally is a global concern since it directly impacts human welfare since 1.8 billion consume contaminated drinking water with feces are at risk of dysentery, typhoid, polio, and cholera. Environmentally, contaminated wastewater will reduce the aquatic ecosystem's biodiversity due to the spread of aquatic diseases and dead zones.
Treatment does occur, especially in high-income countries, where 70% of municipal and industrial wastewater is treated, but the percentages drop significantly in middle and low-income countries. In Upper and lower-income countries, the estimate of treated wastewater is 38 and 28 percent, respectively. Low-income countries treated wastewater is 8 percent. This results in over 80 percent of wastewater that is largely untreated being discharged eventually into natural water bodies.
Technology (including disruptive technology) is increasingly being used to better manage water pollution – both in terms of monitoring and treatment.
This is also known as the Fourth Industrial Revolution.
In-pipe robotic mapping and assessment tools detect leaks, monitor wastewater networks and prevent pollution runoff. Fluid Robotics is a startup using robotics and Artificial Intelligence to help water and wastewater network inspections to help cities better manage water pollution caused by untreated wastewater entering lakes, rivers, and groundwater.
San Francisco sewer system is a combined sewer overflow and collects 500 million gallons per day of sewage and storm runoff when it rains. Treating the wastewater is challenging since groundwater, surface water, and seawater can seep into the system. When seawater seeps into the system, there is an increase in salinity and conductivity; however, measuring the amount of seawater being conveyed into the system by measuring conductivity is possible. Using IoT sensors, San Francisco piloted a project to measures conductivity, turbidity, ph Level, and oxidation-reduction potential, which is a measurement of how much of the contaminants have been broken down by the water. Data is transmitted via an ultra-narrow band signal that can pass through material and dirt before going into the cloud via cellular or satellite connection. 3D-PAWS is an innovative 3D-printed monitoring system to reduce the costs of monitoring.
Earth observation from satellites and Drones/UAVs are a relatively new approach to monitor water quality from space for some parameter (e.g. chlorophyll indicating algal blooms, sediment, cyanobacteria, etc.). For example, GEO AquaWatch is an initiative of the Group on Earth Observations (GEO) to build global capacity and utility of earth observation derived water quality data, products and information to support water resources management and decision making. Many of these approaches leverage the rapid growth in availability of satellite information in the public domain and analytical tools such as Google Earth Engine. There also appears to be significant potential to use machine learning and other AI approaches to help fill gaps and estimate other water quality parameters to support decisions. A major challenge remains access to even basic consistent data services on water quality across the world.
Wastewater treatment plans monitor methods to perform processes control, optimization, and compliance from the inlet to the outlet at every treatment stage. Monitoring also occurs at the sewage pumping stations to ensure there is no breakdown. Recently, water companies in the UK are now adapting their methods to increase their assets' overall lifespan instead of replacing it. Anglian Water is detecting blockages via noncontact level monitors alongside intelligent pump starters. The system acts as an early warning to prevent potential blockages by issuing a pump reversal command. For five months, the system avoided 11 failure events.
As an ongoing effort to fight the COVID-19 epidemic, many municipalities worldwide are monitoring their sewage to detect fecal shedding of the COVID-19 virus. Currently, detection does not provide any indication of disease prevalence in a community. Still, it is an effective early warning system to detect trends since it has been estimated that fecal shedding occurs about a week earlier before an individual displays symptoms if at all (asymptomatic) or if there are delays in diagnostic testing. The Netherlands performs sewage monitoring weekly scale at 300 wastewater treatment plants and then incorporates the data into their COVID-19 dashboard.
There is a growing range of innovative solutions being proposed, especially by a range of start-ups in the developed and developing world to use new technology to treat the growing problem of water pollution.
Constructed wetlands are a relatively low-tech solution but still disruptive in impact in transforming a local area. These are also now ways in which this concept is being modernized with improved processes and technology (e.g. floating islands).
An example of a really “disruptive” technology for addressing algal blooms even in large lakes, reservoirs, or ponds is the use of Ultrasonic Algae Control systems.
According to a recent Nature study, researchers are close to developing geopolymer filters for water treatment using 3D printing, direct foaming, or granulation. The geopolymers offer a pore diameter of 2–50 nm, as well as good mechanical properties and may offer a much cheaper, stable and a more durable alternative to purify water.
Some tasks such as cleaning sewer systems (which, when choked up cause localized water pollution and problems to those discharging into these systems) are particularly hazardous to humans and robots could be deployed to undertake these tasks.
Lebanon’s tech start-up Mrüna has come up with an innovative digital solution to treat wastewater. It has developed a nature-based rapid tech and low-cost system called as BiomWeb which uses IoT to treat wastewater onsite with a series of water tanks that imitate aquatic habitats found in nature, saving transportation costs of waste and recycled water. The solution eradicates the need for added chemicals, desludging, or vast infrastructure investment. The innovative idea also has won the global tech innovative competition organized by Global Infrastructure Hub- a G20 initiative.
Biogas systems have been in use for decades in China (42 million micro-scale digesters) and India (about 5 million) and are getting popular in other parts of the world to provide energy resources from livestock and human waste. Two towns in Cameroon are installing biogas systems to convert human waste into sustainable energy that can provide fuel and electricity for local communities. Rest of the waste released during the process can be used as fertilizers. It is estimated that the project has the capacity to reduce greenhouse gas emissions in the vicinity by 60%.
Accra, Ghana is turning raw sewage into green energy using the country’s first modern fecal treatment plant protecting thousands of residents against Cholera. The sludge produced in the process is then used to make compost and fish feed for the communities.
In densely populated slum areas in Kenya (e.g., Kibera), bio-digesters have been linked to communal toilets to generate gas for cooking while improving sanitation services.
An EU-backed All-gas project led by Aqualia, in southern Spain, is converting algae into biofuel using wastewater. At present, the project can fuel up to 20 cars with the biofuel obtained on 1 hectare of land while treating the wastewater produced by 5,000 inhabitants. The project currently saves the emission of >180 tons of CO2 per year in wastewater treatment and close to 100 tons by generating biofuels. The project final phase will span 10 hectares of land, equivalent to ten football fields. Biomass residues from the processes involved are also sent to the anaerobic digesters as feedstock. CO2 emissions from electricity generation are also consumed by the algae, which leaves purified water ready for reuse.
Treating wastewater has a very high energy cost. The two main methods to reduce the external energy footprint are to reduce electricity and generate electricity. Utilities are now decreasing their financial cost and promoting sustainability by exploiting the fact that wastewater has an economic value. The energy in organic matter sewage is five times greater than the energy required to treat the wastewater. Many utilities have target dates to become net-zero energy and sell power back to the grid, such as Chicago, UK, Denmark, etc. Wastewater treatment plants use bacteria to break down organic carbon, but success depends on having ideal food, temperature, and oxygen.
Of all the processes, the aeration phase requires a quarter to half of the energy requirements since air is diffused into the wastewater through small holes. An alternative to aeration is membrane aerated biofilm reactor, which is to insert porous membrane tubes. A blower inserts air into the tubes, and bacteria gather outside the tubes and use the oxygen. This method is four times more efficient than aeration.
Converting the waste into biogas is performed in an anaerobic digester. Bacteria convert organic solids into methane and carbon dioxide. Production of biogas can be supercharged with the introduction of fats oil and grease (FOG), where a pilot study in New York found five times increase in biogas production with the introduction of bakery waste and FOG.
Waterchain is using blockchain to create a decentralized water fund to help improve the water quality worldwide. Harnessing the power of crypto capital, the company is creating smart contracts enabling investors to easily select water projects and share in the profits. By deploying token capital ground-breaking technologies and service companies are funded to radically transform the pace of water treatment.
Stickney Water Reclamation Plant operated by the Metropolitan Water District of Greater Chicago is the world’s largest nutrient recovery facility. More than 85 percent of phosphorus and up to 15 percent of the nitrogen is been extracted from wastewater streams at the Stickney plant which has the capacity to create 10,000 tons of high value fertilizer annually that benefitting farmers while promoting water quality downstream.
The world’s coasts are both densely populated (10 percent in coastal areas less than 10m above sea level and 40% within 100 km of the coast) and subject to a range of challenges like rising sea levels and coastal storms and other disasters. One recent study suggested the atoll islands will become uninhabitable by the mid 21st century since coastal flooding will contaminate freshwater supplies with seawater and impact infrastructure. As more water in extracted in coastal settlements, seawater intrusion into coastal freshwater aquifers is becoming a significant problem threatening water and environmental security since it takes less than 1% of seawater to make freshwater unfit for drinking. Environmentally, wetlands in developing countries are highly susceptible to 1m sea-level rise and salinization as a World Bank publication estimate for 76 countries is that 66 percent of the Global Lakes and Wetlands Database coastal wetlands are at risk. Technology is evolving to better understand these changes as well as manage the problem. This includes the increasing focus on using solar desalination for potable water especially in small islands and remote coasts. See below some examples of the many plug and play units being developed.
In Orange County, California, US, the local water district, operates the world's largest water purification system, the Groundwater Replenishment system (GWRS) for indirect potable reuse. The system takes highly treated wastewater that would have previously been discharged into the Pacific Ocean and produces high quality water, using an advanced three step purification system consisting of microfiltration, reverse osmosis, and ultraviolet light with hydrogen peroxide. 100 million gallons (379,000 cubic meters) of high-quality water is produced every day, which meets or exceeds state and federal standards for drinking water.