Wastewater Treatment: Out with Conventional, in with Sustainability
Water is one of the world’s most vital resources. It is critical to the survival of every living creature on the planet. The average human can only go a few days without consuming water in some capacity. Health experts stress drinking fluids throughout the day to remain properly hydrated. However, in some parts of the world, water is hard to obtain. Either there are no sources close by, or there is an improper management system that makes it difficult for people to obtain water. To compound this issue, people lack water in some places, while in others, the water is simply unfit for human consumption. This water is teeming with pathogens, salinity, and toxic minerals due to pollution. With the threat of disease from contaminated water, water and wastewater treatment has become the standard in many places. Wastewater effuent from homes, buildings, and factories in many countries are also treated via wastewater treatment systems before being discharged back into surface waters. Municipalities treat water so that it may be used for drinking, and municipalities and industries treat their wastewater so that it can be safely discharged into surface water bodies without environmental damage.
However, as with most things, there are always exceptions. In this case, there are businesses and municipalities that do not treat their wastewater, bringing harm to the local environment. In addition, even if wastewater is being treated and discharged, that does not mean that water is being saved. Industry and Municipalities alike, draw from freshwater sources either in the ground or on the surface for their purposes. These sources may not always replenish themselves this quickly. If the groundwater or surface water reserves are not replenished, they will eventually be exhausted. Therefore, consideration needs to be made for sustainable water treatment methods. But, what does it mean for a water or wastewater treatment process to be sustainable? How will it improve upon what is already conventionally being done?
Conventional wastewater treatment
Before diving into what sustainability means with regards to wastewater treatment, it would be beneficial to mention conventional treatment methods. These conventional wastewater treatment methods are most commonly used in central wastewater treatment plants. These plants treat wastewater from both municipalities and industries. The process consists of three to four steps: pretreatment, primary treatment, secondary treatment, and occasionally tertiary treatment.
Pretreatment: Consists of course solids removal of any large objects from cans and sticks to eggshells and sand as well as fats and oils. Basically, anything that can cause clogging in pumps or pipelines.
Primary Treatment: Consists of the removal of thick solids in the form of sludge. This is most typically done by sedimentation in a large tank that allows heavy solids to settle to the bottom while grease and oils rise to the top.
Secondary Treatment: Degradation of any biological constituents by way of aerobic biological processes such as a fixed film activated sludge process. These treatments use bacteria, enzymes and protozoa that consume the biological material in the solution.
Tertiary Treatment (optional): in some cases, there is still matter that should not be released into the environment. These contaminants could be toxins, nitrogen, phosphorus, or micro-organisms. Treatments for these include disinfection, denitrification, enhanced biological phosphorus removal, and filtration.
What would make wastewater treatment fit the description of “Sustainable”?
Now we need to briefly discuss what it means to be sustainable. A hard and fast definition is difficult to come by. A quick Google search will tell you that sustainability is the “avoidance of the depletion of natural resources in order to maintain an ecological balance”. That’s pretty simple. We need water, so we need to avoid using all of it. It's the same with a lot of natural resources. Therefore personally, we think that definition is a little lacking because humans make everything so much more complicated. With that in mind, I find this definition to be a bit more appropriate:
“ Sustainability is the process of maintaining change in a balanced environment, in which the exploitation of resources, the direction of investments, the orientation of technological development and institutional change are all in harmony and enhance both current and future potential to meet human needs and aspirations.”
-- T he World Commission on Environment and Development
Now we have added the human element. First, this description uses the word “exploitation,” a more accurate description of our use of resources. There is also a mention of investments because that is a big concern for municipalities and corporations alike. “Sure, this is good for the environment, but how much is it going to cost me and what kind of returns on my investment can I receive?” Then the description touches on “the orientation of technological development and institutional change”. It’s easier to champion sustainability when you have the technology and the social organization to do so. One point without the other makes it a bit more difficult, if not impossible to implement. There are countries that have the technological ability to do amazing things for the betterment of their people, but the government refuses to allow its use for whatever reasons. On the other hand, a country wants to improve life for its citizens, however, they do not possess the technological solutions that may be required.
All of the above need to reach a point of harmony, a balance where the resource is being used as efficiently as possible, at a cost value that someone is willing to invest. This is in addition to the best technology and institutional backing there is to offer. All of this must also “enhance both current and future potential to meet human needs and aspirations.” Sometimes an idea is environmentally sustainable, but it isn’t sustainable to human needs and wants. Luckily, this isn’t always the case.
Making wastewater treatment sustainable can be feasibly done to meet the definition of sustainability described above. The general idea is to retrofit centralized municipal wastewater treatment plant and implement decentralized wastewater treatment units to treat industrial/commercial wastewater. This approach enables the reuse of wastewater, the recycling of certain contaminants, and a reduction of hazardous sludge. In addition to, optimized space footprints and allowing for lower capital and operating costs. These goals can be met with the use of advanced and innovative wastewater treatment technologies for these applications.
How is this approach an improvement over conventional methods?
Sustainability does not always come at a great cost. In this instance, by using wastewater treatment systems that can accomplish things like the one described above, sustainability can bring about less expensive and more reliable treatment.
One of the biggest issues with conventional treatment is that it is often centralized. This is useful for more densely populated urban and suburban communities. However, by sending waste to one plant, there is no guarantee that all potential pollutants will be removed. Treatment facilities such as these tend to be geared toward treating domestic sewage and are not necessarily equipped to deal with certain toxins, minerals, or organisms that would come from an industrial facility. Therefore, if a company doesn’t want to spend the money to discharge its wastewater, they end up dumping it into lakes or rivers or other surface waters. Were industrial companies to use advanced decentralized wastewater treatment units that were implemented on site, they could treat specifically for the contaminants they are producing. Therefore, they would not need to spend additional money for discharging raw wastewater to a centralized wastewater plant or pay any fines for breaking regulations.
Conventional systems many do not often allow for the reuse of water once it is treated or even recycling the more useful contaminants. Dumping treated water back into a stream is not as sustainable as reusing it. Although suitably treated water won’t harm the environment, towns and businesses still would need to draw from primary sources which deplete these resources. Reusing wastewater for non potable applications, reduces the need for this practice and so the rate of source water depletion could decrease.
As a supplement, identifying potentially useful constituents in wastewater, could lead to recycling. Fish farms and slaughterhouses produce lots of fats and oils. If a wastewater system could isolate them, the fats and oils could be used for energy purposes, possibly even in the same facility, saving them money on power consumption.
Sludge is a typical byproduct of wastewater treatment. It can be produced in large volumes and can also be hazardous depending on the wastewater contaminants and any additives introduced during treatment. While it would be ideal to reduce the amounts produced, sludge can be quite useful in certain applications. If this sludge is not classified as hazardous. One application, is as a soil enhancer to organic fertilizer on a farm instead of chemical fertilizers. This way, no associated cost goes into transporting and disposing of hazardous sludge. It instead can potentially be purchased by farmers or horticultural businesses.
With the proper technology, less space can be used for a treatment plant. Conventional central wastewater treatment plants cover large areas of land to compensate for the many tanks, basins and piping required to treat the wastewater. Sustainable advanced wastewater treatment systems are smaller in footprint, either centralized or decentralized. The smaller land requirement means less is spent on construction and land development costs.
Potentially sustainable treatment methods
The technology for more sustainable wastewater treatment already exists. This technology is also cost effective and more efficient than conventional treatment processes used in most places. Each stage in the treatment process has different options for what technology can be of use, and this can depend on the contaminants to be removed. Most sustainable wastewater treatment solutions are designed specifically for those constituents. Non-chemical water treatment processes are some of the most sustainable processes available.
Reverse osmosis desalination is a prominent solution in some tertiary wastewater treatment applications. In particular, its potential uses in these treatment plants make it particularly sustainable, by giving areas with few freshwater sources a way to obtain fresh water. It works well as a tertiary polishing treatment to remove dissolved contaminants that were not treated in previous treatment stages.
Ultraviolet disinfection acts as an alternative to chlorination. Chlorine is added into effluent water in order to oxidize any micro-organisms and render them ineffective. However, chlorine is a volatile substance and can result in the formation of harmful disinfection by-products. UV disinfection, on the other hand, is a physical process and only requires proper prefiltration without the addition of chemicals to nullify micro-organisms including cysts, viruses, and bacteria.
is the sustainable answer to chemical coagulation, where chemicals are added into the effluent to cause the solid particulates to agglomerate and fall to the bottom of a clarification tank. The chemical coagulation process results in a large volume of hazardous sludge. Electrocoagulation typically has no need for any chemical additives except for potential pH adjustment. Therefore, this results in lower volumes of non-hazardous sludge that can be easily dewatered. The dewatered sludge can be disposed of or used as a soil ElectrocoagulationAnother treatment option is used earlier in the treatment process. additve in combination with organic fertilizers and sold to agriculture companies.
Sustainable wastewater treatment is within our grasp and -- you can be a part of it with some help. Genesis Water Technologies, Inc. is dedicated to protecting our environment and saving our water supplies, all while helping businesses and municipalities save money and improve their process efficiency. We offer the specialized sustainable water treatment solutions indicated above. We can provide a single system or a custom engineered process treatment solution based on your specific needs and the contaminants in your wastewater source.
Learn more about how your wastewater treatment process could be optimized to be more sustainable by contacting Genesis Water Technologies on its company page.