Introduction

The Agenda for Sustainable Development Goals prioritizes achieving sustainability in wastewater management. Overall, achieving more sustainable wastewater management techniques will need a holistic and balanced approach to assessing the overall sustainability of a management plan. 

Promoting the adoption of wastewater treatment procedures that are safe, inexpensive, and widely available is a step toward long-term wastewater management. Current technologies are coming with new wastewater management techniques that are proven efficient in achieving long-term water resource management sustainability.

Chemical, biological, and physical contaminants can all be found in wastewater. This makes it potentially dangerous for human usage. If untreated wastewater enters the public water system, it has the potential to cause serious sickness. After treatment, most wastewater is normally discharged back into the environment.

A non-sustainable wastewater management approach might have long-term consequences that go beyond the local operational area and even into future generations. In this context, existing wastewater sustainability indicators that have mainly focused on environmental stresses while ignoring societal consequences should be updated to include present and intergenerational balanced impacts. 

Furthermore, designing wastewater management systems that are better linked to wider community demands should be addressed. Instead of concentrating nutrient fluxes in one receiving water body, reuse of treated wastewater and management of solid residuals might be better linked with local agriculture practices, re-distributing and returning nutrients to the surrounding ecosystem.

Traditional Methods

Depending on the water quality of the influent and the effluent discharge standard, wastewater treatment plants are built to have several water management techniques in combination with different water treatment equipment. Traditional wastewater management techniques include pre-treatment, main treatment, and secondary treatment.

Filtration, flocculation, activated charcoal, and ion exchange resins have all been used in the old days to remove metals from wastewater. Treatment goals ranged from around 1900 to the early 1970s and included

(i) The removal of suspended and floatable debris from wastewater

(ii) The treatment of biodegradable organics (BOD removal), and

(iii) The eradication of disease-causing pathogenic microbes.

 From the early 1970s until the early 1990s, wastewater treatment was primarily concerned with aesthetic and environmental issues. The previous duties of reducing and removing BOD, suspended particles, and harmful microorganisms were carried out again, but at a higher level. Nutrient removal, notably nitrogen and phosphorus, began to be addressed, especially in some streams and lakes.

Traditional wastewater treatment plants (WWTP) are big outdoor installations with various negative characteristics. The look and smell of the bulky, industrial water management systems are two of the most significant. They are unpleasant, but they also necessitate large infrastructure investments since investors must not only construct the physical facility but also plan and develop the whole infrastructure for transporting wastewater to the WWTP. 

Conventional Methods

The choice of a particular conventional method is largely influenced by several parameters, including waste type and concentration, effluent heterogeneity, the necessary level of cleaning, and cost. Due to improved performance, availability, and low cost of raw materials, microorganisms, including bacteria. The use of several wastewater management techniques by both living and non-living microorganisms to remove and recover toxic or precious metals from industrial wastewaters has gained popularity over the years.

Biological Methods

Bacteria, nematodes, and other tiny organisms are used in biological treatments to decompose organic wastes through natural cellular processes. Garbage, trash, and partially digested meals are all common sources of organic matter in wastewater.

Biological wastewater treatment is frequently employed as a secondary treatment technique to remove material that has not been removed following the first treatment, such as dissolved air flotation (DAF). 

Physicochemical Methods

The segregation of colloidal particles is the primary goal of Physico-chemical wastewater treatment. This is accomplished by the use of chemicals such as coagulants and flocculants. These alter the colloids’ physical state, allowing them to remain in an endlessly stable condition. As a result, form particles or flocs with settling qualities. Coagulation, flocculation, and sedimentation are the steps of the physicochemical process. There are, however, some arrangements in which all steps are completed in the same unit.

Tertiary Methods

Tertiary therapy is an advanced wastewater management technique that is more sophisticated and demanding. Primary and secondary treatment normally only cleans wastewater to the point that it can be safely discharged into the environment. On the other hand, Tertiary treatment can purify water to the point that it can be reused in water-intensive activities or even used as drinking water. Tertiary treatment is not used in all wastewater treatment plants. For many purposes, primary and secondary therapy are typically adequate.

Pros and Cons of Treatment Methods

The parameters of the effluent will thus determine the procedure to be utilized. Each treatment has its own set of restrictions, including cost, feasibility, efficiency, practicability, dependability, environmental effect, sludge generation, the difficulty of operation, pre-treatment needs, and the development of potentially harmful by-products. 

Just a handful of the different wastewater management techniques now listed are frequently used by the industrial sector for technological and economic reasons. In general, physicochemical and/or biological methods are used to remove contaminants from effluents, with research focusing on more cost-effective combinations of systems or novel alternatives.

Pros: 

• The clarification of water is an important phase in the wastewater treatment process. Gravity settling removes suspended materials, resulting in a clear liquid effluent.
• The various treatment technologies for heavy metal removal in wastewater.
• Silt removal is done with sand and grit removal equipment, which recycles wash water fast and reuses it for irrigation or more washing.
• After being processed at a wastewater treatment facility, oil and gas wastewater can be utilized for dust suppression.
• Protect the public’s health and safety. Lead and other metal pollutants remain on the road surface and are not washed away by rains. These pollutants are removed by conventional wastewater treatment.

Cons:

• Pumping out the system on an annual or bi-yearly basis is essential to eliminate the build-up of sludge. Also, the scum that clogs the waste flow and prevents the system from operating properly and efficiently.
• Treatment plants might get stinky if they are not properly maintained.
• The sewage is naturally broken down thanks to a careful mix of microorganisms in the treatment plan.
• The expense of a sewage treatment plant might be considered a drawback compared to a connection to your local town sewage or a septic tank setup.
• To function, the wastewater treatment facility requires a steady supply of power.