Did you know that even today, many countries lack proper wastewater treatment? Moreover, polluted runoff causes various troubles to the environment and humans.
That’s why Sustainable Development Goal 6 aims at improving water quality worldwide by 2030. Let’s talk a bit about the processes involved in treatment and the types of treatment plans.
Processes Involved in Treatment
All treatment processes fall into two categories: physical and biological. The first category usually includes settlement and flotation. The other includes aerated lagoons, activated sludge, or trickling filters. In both cases, sewage must go through the infrastructure to reach the treatment plan.
Phase separation means filtering the impurities and converting them into a non-aqueous state. For example, it may recover grease for saponification, or oil for fuel.
Processes that remove solids from wastewater usually include gravity and a grit channel. It’s the primary treatment of sewage and treats various types of wastewater. More advanced units can also remove floatings grease and even solids, such as wood chips. There are also special containers that separate non-polar liquids.
This process usually reduces the toxicity of certain contaminants. Additionally, it converts some organic compounds into water and carbon dioxide. It’s also known as secondary treatment.
Biochemical oxidation usually removes organic compounds. Those later become a food supply for the ecosystem. It is also popular in sewage treatment and is good for most industrial wastewaters.
After biochemical oxidation, some pollutants can still remain in the water. That’s why chemical oxidation comes in, to remove various bacteria and viruses. The process usually includes adding ozone, chlorine, or hypochlorite to polluted water.
Polishing is the final process in wastewater treatment. It adjusts the pH level in the water and minimizes chemical reactivity. Carbon is sometimes used to absorb the contaminants. It makes the calcium carbonate and fabric filters a common method in treatment.
Types of Treatment Plans
Treatment plans fall into three categories, depending on the type of wastewater. So, we have sewage, industrial, agricultural, and leachate treatment plans.
Sewage Treatment Plans
These plans usually include treatment for solid material removal. Additionally, secondary treatment covers digesting organic material. In some cases, these plans might include disinfection to kill bacteria. Some towns also have factories that release the industrial water into the drinking water system.
Tertiary treatment, or the final, “polishing” process, is increasingly applied in industrial countries. It includes microfiltration and certain membranes. After the treatment, the water is almost identical to waters of natural origin. This treatment sometimes removes nitrates via special denitrification processes. Also, ozone generators can be used for ozone treatment, and the latest technology includes aerobic granulation.
Industrial Water Treatment Plans
Treatment of industrial water can be a complex and expensive problem. Most refineries and chemical plants have an onsite solution to regulate the number of contaminants in wastewater. Some plans also include constructed wetlands which provide excellent onsite filtration. On the other hand, some industrial plants that produce lots of waste need to recycle the water during use, before it has to be cleaned or filtrated. It usually includes processes such as paper or pulp production.
Industrial treatment plans are mostly used where sewage treatment can’t treat the water. Also, costs are sometimes reduced by converting wastewater to reclaimed water. Usually, industrial treatment plans include an API oil-water separator, a clarifier, a roughing filter, a carbon filtration plant, or an EDR. In some cases, it might include more than one of the specified units.
Agricultural Wastewater Treatment Plans
Agricultural wastewater treatment is crucial in plants that perform operations with animals. It might include operations such as egg or milk production. However, to reduce the costs, the land should be able to have ponds, settling basins, and facultative lagoons.
Leachate Treatment Plans
These are mainly used to remove landfills from leachate. It can be done via biological treatment, ultrafiltration, active carbon, or electrochemical treatment. Also, some treatments include the Reverse Osmosis process.
Countries in the EU need to satisfy the Urban Waste Water Treatment Directive. It sets standards for the disposal of sewage, which is similar to the Bathing Waters Directive.
The United States
Every state in the US needs to meet specific EPA standards. It consists of the Secondary Treatment Regulation and Effluent Guidelines. The first applies to municipal sewage treatment plans, while the latter includes guidelines of industrial facilities.
As you can see, even developed countries have problems with polluted water. That’s why many countries continually improve their rules and regulations related to the environment. However, with the proper treatment plans and processes, we are sure that the situation will improve by the end of the next decade.