A thought to commemorate World Environment Day amidst pandemic
The interjection on common grounds for water system management and circular economy initiatives gives a vast alignment for opportunities in the field of sustainable environment.
The concept of circular economy is outlined on six factors i.e Reduction, Reclamation, Reuse, Recycling, Recovery, Rethink.
The reduction of the generation of wastewater is a major step taken towards sustainability as the less the wastewater generation the lesser will be the treatment approach cost.
Reclamation is the approach taken to reclaim the already generated wastewater by effective treatment methods.
Reuse is the step where the non-potable water is used as an alternative for the freshwater in industry.
Recycling is a vital step where water after treatment has been transformed into potable and it replenish the scarcity of water to some extent.
Recovery is the major approach undertaken to segregate nutrients and energy generation from the sludge after water treatment. The literature review has shown the amount of energy generated from such waste is so much that it can run the machinery in industry without use of external energy supply. It depicts a sustainable approach towards conservation of energy.
The last approach is a thought-provoking one as we need to rethink a sustainable economy where generation of waste and emissions are minimal.
The concept of circular economy is the decisive and vital step for the water and waste-water sector. With systematic thinking and environmental stewardship it becomes an important factor for environmental management and planning.
The management of water and wastewater is one of the biggest challenges for the implementation of circular economy as most of the industries depends on water and few have the access to clean water resources which further restricts the productive capacity and the profit generation. The wastewater generation leads towards environmental disruption is an integral part of water management as half of the global freshwater (2212 km3 per year) is released as wastewater in the form of industrial and agricultural effluent in the environment. Out of the whole, 44% of global freshwater (1716 km3 per year) is primarily consumed by agriculture through evaporation in irrigated cropland.
Ellen MacArthur Foundation gave the Circular Economy Systems Diagram where the focus doesn’t reflect the water systems, e.g. manufacture/remanufacture, landfill, etc. so an alternative approach of Circular Economy Systems Diagram specific to Water System is explicated explained in the following diagram:
The two halves of the systems diagram shows human and nature managed water management which is also depicted as biological and the technical part.
The complex system known as water is held by the soil, vegetation, a surface water body which percolates in ground and aquifers.
Nature Managed System
Within a given basin, the natural water cycle acts to re-optimise, reuse, and replenish water:
- Re-optimise – The naturally available resource helps to maintain a sustainable economy and biodiversity. The ecosystem adapts itself to the inevitable change.
- Reuse – The reuse of water to cater to the need of demand for the industrial purpose
- Replenish – the natural cycle completes its cycle where water is replenished to the environment through evapotranspiration, infiltration or surface water flows.
Human Managed System
For the human managed system the water circularity is impacted by the intervention of humans. The following are the methods implemented for the same:
- The overuse of freshwater exceeds its replenishment capacity
- The implementation of conventional irrigation methods for faster yields in crops leads to a major depletion of water resources
- The generation of wastewater more than the freshwater leads to the scarcity of water for potable use
These outcomes have a detrimental effect on natural water cycle therefore it has impact over the economic and environmental losses to meet the human needs
Dimensions of Water Use
The fundamental need for the survival of humans is by use of water. There is no substitution offered for the vital role imparted by water resources.
The dimensions of water are also mapped against the demands of Food – Water – Energy Nexus.
Water as a source of service
Water plays a fundamental role for the purpose of sanitation in our home and workplace, for the purpose of cooling and heating of the buildings and industries.
Water in the form of energy
Water and its physical properties can be utilized can act as a source of energy.
- The mass and energy within the stream of water can be saddled to create hydro-electric vitality
- The thermal entities empower it to assimilate warm vitality from the environment or human action that can be extricated (e.g. water source warm pumps and vitality collecting from sewers)
- Bio-thermal vitality such as anaerobic assimilation from civic sewage
Water as a carrier
As a fluid common asset, water may be a commonly accessible and all inclusive carrier within the normal and built environment. In both settings water is acting as a carrier of chemicals, particles and droplets (broken up and suspended state) which therefore justify the potential asset or pollutant.
- In agricultural surroundings, there is a huge generation of nitrogen and phosphorus from fertilizers in the environment
- Within municipal and industrial settings, it could include trace chemicals in treated water and wastewater
Removal of these chemical and nutrients may be driven by economic reasons, but in many situations it is driven (by regulatory requirements), for pollution prevention and environmental protection, e.g. recent limits on nitrate and phosphate is being implemented in the European Union.
Extracting the nitrogen and phosphorus from final effluents at wastewater treatment plants before discharge provides the following benefits:
- The quality of flow helps in increasing the opportunity for water reuse and reduce cost of treatment for downstream users (e.g. for drinking water)
- Environmental impacts are decreased
- Systematic treatment
- The water system is sub systems approach that includes the industrial, agricultural and municipal systems
- The circular economy opportunities exist for the application of systems
- Systematic approach will augment the assessment of impact and increase the value of the application to minimise the damage
Example and opportunities for Water management for circular economy
Cellulose extraction from waste water
Process: Cellulose extraction from waste water streams involves separation, purification, hygienisation and drying
Dimension: The basic carrier is water
- optimisation the use of water and energy
- nutrient extraction
Fertilizer and pesticide application
Process: Application of fertilizers and pesticides in agriculture
Dimension: Water used as an applicant
- Nutrient capture from chemicals and nutrient runoff or biomass
Process: Treatment of sludge for energy generation and generation of carbon footprint is less
Dimension: Source of energy is water
- Byproduct utilisation
- Treated effluent reuse
Process: Capture and treat livestock farm effluent to ensure water quality
Dimension: Water as the medium
- Nutrient utilisation and
- After anaerobic digestion the generation of energy from sludge
Process: The greywater is reused for non-drinking purposes
Dimension: Water as a source
- Greywater processing for byproduct extraction
- Processing of thermal energy
Wastewater Treatment & Industrial Symbiosis
Process: Process treatment of sludge for energy Compared to other methods, it offers a significantly smaller carbon footprint
Dimension: Water as a source of energy
- Utilisation of byproducts
- Reuse of treated effluent
Composed by Dr.Debleena Bhattacharya, Assistant Professor, Marwadi Education Foundations Group of Education (MEFGI), Gujarat and Guest Editor, InnoHEALTH magazine