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Wastewater Treatment Systems for City-Based Municipal Drains for Achieving Sustainability


Currently, drains in several cities carry both rainwater and untreated greywater with black water from settlements nearby. In emerging economies, cities often become hubs of illegal and unauthorised colonies which thrive in the vicinity of stormwater drains. These create a unique pressure on the infrastructure and pose a challenge for civic bodies for ensuring adequate outflow quality as per environmental discharge norms. The flow characteristics (variable, seasonal, minimum or continuous flow) and structural constraints (the bed and site complexity) in the design of these drains restrict the options for implementing large wastewater treatment plants. In addition to the above, the techniques that rely heavily on structural, mechanical and energy inputs are economically not feasible and demand more maintenance, which acts as hindrances in these harsh environments. In these scenarios, human health is a critical factor, as frequent exposure to sewage without any protective equipment during maintenance could lead to health hazards and high-stress levels. The utilisation of decentralised and distributed wastewater treatment systems offers an in situ choice for achieving the desired result in quality and nutrient removal in the influent. These systems enable the water to be safely discharged to rivers or channelised for agriculture or industrial purposes. Furthermore, the solid fraction in the sewage is extracted as manure or composted after curing. The selection, design and implementation with maintenance are essential for improved efficiency and productivity of the system. Therefore, an investigation into such processes presently utilised, and a few other possibilities are discussed in this paper. This paper aims to establish various concepts and schemes that municipal corporations could adopt sustainably for efficient treatment within the limited spatial and temporal boundaries offered by city drains.


In 2020, archaeologists unearthed a drain estimated at least 500 years old or more, 30 m in length, at the iconic Red Fort in Delhi [1]. This finding indicated that Delhi’s drainage system must have had a rich history. It predominantly dates back to the pre-Mughal era, when smaller drains from the inside wall limits of the city were discharged into larger ones running through the boundary outside of the city and mixed with a river. During medieval times, maintenance was carried out and adjusted to accommodate changing scenarios. The presence of a structured sub-soil masonry drainage system and network during Shah Jahan’s reign is an example cited by Prashad [2].

During British rule, the Delhi Municipal Commission (DMC) was established under Act no. 26 of 1850 in 1862. The Delhi Municipal Committee was constituted in 1863, while it was only 20 years later that the first such committee came into existence [3]. Prashad [2] reports that as early as the 1870s, sewage management, especially drains with overflowing waste, was a source of diseases. Deaths were reported in the city due to toxic gases emitting from them. DMC’s actions were considered a failure by the then residents. The wastewater from households could not be transported to river Yamuna due to the destruction of channels caused by their neglect over a century.

Subsequently, structural modifications were carried out at several places by different agencies from time to time.

Meanwhile, the population of Delhi increased nearly thirty-one times between 1941 and 2018 from 0.92 million [4] to 28.5 million [5, 6]. A website cites the “World Population Prospects” of the United Nations which estimate the figure to be 31.18 million in 2020 [5].

The considerable influx and population growth hence created tremendous pressure on infrastructure, including municipal drains. In addition, the constraints of development and socio-political aspects prevented timely maintenance of its civic infrastructure. Unauthorised settlements came up near the drains. As a result, steadily, the stormwater drains in Delhi started functioning predominantly as sewage drains.

As per Delhi Jal Board’s estimates, Delhi’s estimated wastewater generation is more than 3760 MLD against available treatment capacity of 2259.89 MLD in 20 STPs, operating at 87.76% capacity (Economic Survey, 2020-21, Government of NCT of Delhi) [7]. The sewerage network is around 8800 km in length, with the internal and peripheral sewer consisting of 200-km trunk sewers supported by 58 major sewage pumping stations [7]. The sewerage system serves 55% of the population of Delhi, while drains also carry the sewage flow from entering stormwater drains and laying sewers in unauthorised colonies.

Wastewater recycling and reuse are an anchor for achieving long-term water security and equity. The subject of this paper assumes importance in establishing a circular approach focussed on municipal drains. It is worth briefly covering the nexus between circular economy, sustainability and wastewater. The concept of circular economy (CE) took shape in the 1980s [8,9,10,11], although it has also been attributed to Malthus [12]. A formal definition was introduced in the 1990s. CE promotes a circular approach for managing natural resources and materials rather than a linear path comprising of extract, use and disposal. The relationship between circular economy and sustainability has been discussed at micro-, meso- and macro-levels [13].

The management of natural resources such as water in a circular way has been considered essential for furthering circular economy in the urban context [14] and utilising 3Rs (Reduce, Recycle and Reuse) [13].

Wastewater as part of circular economy and water reuse as an aid to attaining sustainability have been discussed through PESTEL analysis, including barriers to water use and possible solution pathways [15]. Wastewater reuse in plantations and constructed wetlands for carbon sequestration and as part of eco-engineering respectively has been illustrated [16]. Selected wastewater treatment technologies could also be classified as nature-based solutions for addressing societal challenges within the context of climate change [17].

Interlinking with SDGs

Sustainable Development Goal (SDG) 6 relates to water and sanitation with 8 targets and associated 11 indicators. The target number 6.3 intends that (sic) [18]

"By 2030, improve water quality by reducing pollution, eliminating dumping and minimising release of hazardous chemicals and materials, halving the proportion of untreated wastewater and substantially increasing recycling and safe reuse globally."

There are two indicators for Target 6.3, namely, the proportion of wastewater safely treated and the proportion of water bodies with good health.

Therefore, in the context of SDGs, importance of integrated management considering not only treatment but a circular approach could establish a basis for equality and equity of water resources in urban settings.

The paper considers the case study of Delhi and its municipal stormwater drains, which have met the fate of turning themselves into domestic wastewater drains due to unchecked discharge from settlements near them. These conditions pose problems downstream as most of them flow into river Yamuna without being treated adequately. In addition, the scenario becomes aggravated during monsoons, with several floodings across the city and the risk of contamination of mixing drinking water and sewage increases manifold.

It is essential to understand the present context of the drains for developing an effective strategy for monitoring and treating wastewater flowing in the drains for minimising the impact of pollution load in basins and rivers. This paper provides an overview of the opportunities and challenges in implementing technological routes for achieving circularity as part of circular economy and sustainability for water conservation.

Present Status of Drains in Delhi

Delhi is divided into eleven administrative districts (refer to Fig. 1). The map can also be viewed at the website [19].

Fig. 1
figure 1

Administrative districts of Delhi [19] (not to scale)

The Union Territory of Delhi has a network of open and closed drains (refer to Figs. 2, 3 and 4). As per the drainage master plan of Delhi, 2018 [20], there are an estimated 2846 drains of 4 ft or above in width with a total length of 3740.311 km under eleven departments including UP Irrigation for Old Agra Canal. Apart from these, 63 drains controlled by the Irrigation and Flood Control Department [21] run into a few hundred kilometres across five blocks, namely Najafgarh, Kanjhawala, Alipur, Trans Yamuna Area and Mehrauli. In addition to these, different parts of the city are connected with smaller drains. These drains feed three major basins. With the increasing population and habitat pressures, most of the settlements thrive near the city drains. Lack of proper infrastructure and policy measures forces households to discharge untreated grey and black water into the nearest stormwater drains. Some of these streams are often utilised for irrigation downstream [22].

Fig. 2
figure 2

A typical polluted stormwater drain in Delhi

Fig. 3
figure 3

A typical partially covered drain in Delhi

Fig. 4
figure 4

A typical open drain in Delhi

The following attributes emerged during the primary survey of drains and interactions with municipal officers and residents along with information based on public domains [20, 23]:

  1. 1.

    Drains feed three major basins.

    The drains in Delhi fall into Barapullah, Najafgarh and Trans Yamuna basins [20]. However, there are several blockages in the flow path due to illegal structures and modification of natural slopes caused by unplanned constructions.

  1. 2.

    Open and covered drains.

    The drains in Delhi have been operating for several decades without major civil and structural modifications. These are fully open in some places while covered in several other sites. The primary reason for construction was creating green spaces or beautification over the drains to prevent eyesore and reduce putrid odour in surroundings. However, in several places, this led to the formation of obnoxious gases, especially ammonia and hydrogen sulphide, due to the untreated water and anaerobic conditions. These conditions caused health hazards and resentments among the residents near the affected drains.

  1. 3.

    Drains of different depths and sizes.

    The complexities of the topography and geography in Delhi have been a significant challenge in mapping and constructing standard size drains. The different magnitudes of constructions warrant drains of various dimensions and carrying capacities.

  2. 4.

    Stormwater drains face increasing pressure from nearby settlements.

    The growing need for shelter for migrants and the poor has forced them to construct dwellings near the drains. It serves as an easy window to discard their domestic (solid and liquid) wastes.

    Also, political patronage is widespread, preventing civic bodies to take necessary actions against defaulters.

  1. 5.

    Lack of proper sewerage network.

    Due to the unplanned growth within the city, several residential pockets in and around Delhi are not connected to the sewerage network. The National Capital Regional (NCR) Planning Board specifies that except in Delhi, where an estimated 80% of the population is covered under sewerage, nearby urban areas have only 5 to 30% coverage [24]. This attribute emerges as a point of concern for ensuring that municipal wastewater is adequately treated before discharge to surface water bodies.

  1. 6.

    Socio-political pressures.

    Delhi’s political landscape is complex, and often different leadership governs at different levels from local to the state. Due to political oversight and the absence of suitable connectors for ensuring wastewater flow to the sewage treatment plants, the sole option for the colonies and dwellers near drains is to dump their grey and black water in storm drains. These result in untreated grey and black water outlets in the stormwater drain.

  2. 7.

    Administrative complexity.

    Drains in a cosmopolitan city like Delhi are monitored by multi-disciplinary and diverse agencies governed by different political powers within a more complex role and responsibility web. These pose a challenge in decision making, e.g. first- and second-order drains under the administrative control of different agencies even though they fall under one zone or district.

Materials and Methods

This paper is a sub-set of a more extensive study conducted for monitoring the health of the Yamuna river. The overstudy involved two phases for deriving and suggesting feasible in situ treatment schemes for wastewater treatment in municipal drains. The methodology for the study is outlined in the succeeding sections.

Phase 1

The first phase of the study involved physical visual inspection undertaken by the study team. This phase also involved the collection of wastewater samples and determination of approximate flow, subject to accessibility.

A physical survey of major and minor drains, along with their final outfall and catchment areas, was completed. Standard android mobile with Google Photo and Google Maps for tracking locations of drains was utilised. The Google Photo application has a feature for storing the geographical coordinates of an image. In addition, a drone equipped with a high-resolution camera (post-administrative clearance) was deployed for aerial survey for collecting imagery data through appropriate video formats. The drone traversed through the length of the drain. The video from the drone and image was referenced and analysed to assess physical conditions and surroundings concerning a drain. The videos assisted the research team in understanding the landscape and extent of development near the drains. The coordinates obtained from imaging and tracking were processed on Google Earth for locating the drains under study. The dimensions and other characteristics of the drains were considered before overlaying the suggested treatment scheme.

Phase 2

An in-depth advanced scientific approach for the assessment of drain topography was adopted for selected drains. Longitudinal (L-) section and cross (X-) section survey using handheld Differential Global Positioning Satellite (DGPS) device and standard levelling work was carried out with the assistance of professional surveyors. The results were analysed for understanding control points, every 500 m with additional parameters such as water level, gradient, slopes and culverts for a specific drain section. The survey results were plotted on AUTOCAD2013 and considered for further processing.

Wastewater Treatment for Municipal drains

Let us consider the categorisation of wastewater treatment systems for municipal drains. These could be classified or categorised depending on several parameters. However, this paper will focus on the in situ remediation of municipal wastewater in urban/city drains.

Wastewater treatment plants could be categorised based on a spatial basis, such as:

  • Centralised

  • Decentralised

The centralised treatment facilities are typically advantageous where a suitable area is available to implement large-scale treatment plants. Supply to these plants is easily connected through pipelines and has a well-defined source for the treated water to be discharged in water bodies or transported through pipelines to the consumer.

On the other hand, decentralised facilities offer the flexibility of treating smaller quantities of wastewater, similar to a grid-based system, which may or may not be interconnected. The source for discharge of treated water is either local or generally reutilised for agriculture or nearby activities.

A second categorisation could be suggested, based on source treatment such as:

  • Off-site

  • In situ

Off-site treatment facilities generally constitute transportation of the wastewater from the source of generation to a separate treatment scheme. This is achieved through a natural drainage system or a pumping mechanism to an entirely different location.

In situ treatment involves installing a suitable remediation system engineered to be constructed inside a drain or a water body (existing or proposed), considering a similar series of steps leading to the desired water quality on the other side of the module. CPCB has also studied several in situ and ex situ models for different drain branches [25].


Delhi had its own set of problems due to the drainage system from the pre-colonial era. The earliest recorded health data pertains to deaths due to toxic gases from sewage systems in the 1880s [26], and a Jaundice outbreak in 1956 [27], attributed to water contamination by sewer drains. These public health incidents eventually led to the first master plan of Delhi in 1961 by the Delhi Development Authority (DDA) [28]. There are several challenges in implementing a standard scheme solution for treatment in stormwater and municipal wastewater drains. Typical are the varying flow characteristics due to mixing grey and black water, source point, constraints in space, shock loading, maintenance aspects, stability and cost implications.

  • Flow characteristics

    The flow in the drains is erratic depending on the population served and micrometeorology. There are pockets where the flow remains steady due to resident population or serving multiple smaller drains. In other cases, discharge is intermittent as people migrate to their home villages or towns at a particular time of the year. These flow changes could also be a result of the varying micrometeorology. However, the pattern of flow in urban stormwater and sewer is an in-depth study and analysis area.

  • Spatial constraints

    The drains come in different dimensions due to spatial constraints. The more planned areas have drains with defined boundary walls, culverts and a stable base enabling easy maintenance.

  • Cost implications

    The economics of scale is a factor in implementing suitable solutions for domestic effluents, especially in drains. Large common wastewater treatment plants are expensive in terms of land and resource consumption.

  • Maintenance

    The maintenance of these systems requires ample time and human resources.

  • Performance

    As these systems work on different loadings, their efficiency and efficacy might decrease over time.

  • Loading

    The uncertainty in assessing reliable organic and inorganic loading parameters makes the operations and maintenance a task.

Design of these systems should be subjected to detailed techno-economic feasibility reports and other environmental impact assessments before being finalised.

Technological Interventions

There are several controlling conditions while customising treatment schemes for wastewater for municipal drains. Therefore, the selection of the treatment technology could follow the proposed function


where T is the proposed treatment scheme for a given drain; q is the quality of wastewater to be treated obtained from its physicochemical and biological analysis; v is the volumetric flow rate, cu.m/h; A is the area, m2; a is the aeration or oxygen available; s is the seasonality of the flow; and a = 1 when conditions are aerobic, a = 0 in anaerobic situations and a = ½ in semi-open conditions,

The design of the system should preferably consider all these factors quantitatively wherever possible.

External influences warrant coverage, such as the political, economic, aesthetics and management of the process deployed.

Outlet or Discharge Standards

Several agencies suggest and prescribe suitable standards for the discharge of treated wastewater from sewage treatment plants (STP) in India. The Indian Standard (IS) 2296:1992 [29] provides five different water quality standards from A to E. The former represents water fit for drinking and the latter suitable for irrigation and industrial purpose. The National Environmental Standards of 2000 under Environmental Protection (EP) Rules, 1989 of India, specify the discharge standards applicable to inland surface waters [30]. The National Green Tribunal (NGT), in its ruling of 2018 (OA: 673) [31], stressed selected quality parameters for considering river water fit for bathing. The relevant parameters, along with their limits, are provided in Table 1.

Table 1: Desired limits of treated wastewater (class D, E and inland surface waters)

The World Health Organisation (WHO) also prescribes limits (WHO guidelines for the safe use of wastewater, excreta and greywater, 2006) [33] for treated greywater reuse for several applications, including in toiler flushing and for irrigation of such vegetables which may be consumed raw. These standards provide maximum tolerance limits for 15 elements and 26 organic compounds deemed toxic to human health present in the soil.

In addition to the above standards, the assessment completed as part of the report (CRDT, IIT Delhi, unpublished) for South and North Delhi Municipal Corporations suggested that in situ treatment schemes for type I could achieve NGT standards for discharge from STP to surface waters. Furthermore, it is assumed that the outlet parameters would conform to acceptable standards for permitting the treated municipal wastewater into either a river body or fit for irrigation or construction and industrial purposes.

Suggested Treatment Schemes

Drains in and around Delhi come in varying dimensions. A primary survey and subsequent study of drains under two municipalities (South Delhi and North Delhi) by the CRDT, IIT Delhi, classified drains depending on their width. Table 2 is an example of a typical drain and its dimensions, with width ranging from less than a metre for smaller ones to more than 9 m for larger ones. There are smaller drains with 1–4 m in width. The depth of drains ranges from 2 to 10 ft. Depending on their final discharge point, the drains are often classified into primary, secondary, tertiary or main and branched. The corresponding drain types (read drain order, e.g. drain type II is read as a 2nd-order drain) are provided in Table 2.

Table 2: Number of drains and dimensions, North Delhi Municipal Corporation [34]

The challenges hitherto mentioned, along with the constraints and complexities posed in modern stormwater drains acting as sewer transportation channels, warrant exploration and installation of in situ treatment plants. A study by IIT Delhi in 2020 [34] as a response to the call of the Hon’ble National Green Tribunal (NGT) on the objective of ensuring an acceptable quality of water into the Yamuna led to compact decentralised designs for treatment of wastewater in city drains. The detailed study proposed several schemes. Figure 5 provides a sample scheme for primary drains and secondary drains.

Fig. 5
figure 5

Sample wastewater scheme for different types of municipal drains for primary and secondary drains

These are two typical process flows that could be adapted for different sizes of drains. The upper one could be utilised for primary drains, while the lower flow could be more suited for secondary or branched drains. Tertiary treatment for primary drains is essential for ensuring that proper treatment occurs before discharge to a surface water body.

It could be observed that the schemes presented have minimal energy requirements and low material requirements while allowing the treatment of influent in a systematic manner for the removal of pollutants as well as contaminants.

Quality Control

These schemes could be utilised for two purposes: replenishing a river’s flow or reutilising it for industrial and horticulture activities. An ideal design for a small urban area would be to circulate the treated water for flushing or toilet purpose to nearby settlements, subject to strict monitoring for ensuring zero microorganisms in the treated water. However, there could be several other iterations that could work in different environments. These need to be investigated in detail. The sub-component of the schemes is well known for their use in the treatment of mix type domestic wastewater. The performance of the in situ treatment plant would be subject to stringent monitoring of physicochemical and biological parameters as per relevant discharge standards and adequate supervision for ensuring streamlined delivery of the desired effluent characteristics.

Advantages of In Situ Approach

The in situ approach offers several features such as ease of installation for shallow depths, customised designs, appropriate for organic and mineral loads, low-energy requirements and ability to recover nutrients depending on the intensity and efficiency of the system. However, the diverse challenges inherent to such systems concerning drains and past performance should be considered.

  • Easy to install for shallow depths

    The treatment options could conveniently be engineered for drains with shallow depths and low water flow rates.

  • Customised design

    The systems can easily be customised as per the overall water quality predominant in the drains.

  • Removal of organic and mineral loads

    These are effective in handling organic loads and, to some extent, in emerging pollutants.

  • Low-energy requirements

    The options provide a low-energy option both in capital expenditure and operating costs.

  • Integration with space limitation

    The design schemes come with the flexibility of adjustment for space.

  • Desired quality for safe discharge to rivers

    These designs can ensure that the discharge parameters meet the prescribed or desirable parameters set by regional or national standards for safe discharge to natural water bodies.

  • Safety

    The process would reduce the existing health hazard arising from the untreated sewage.

  • Natural systems

    Several natural systems could offer a cheap, viable and require minimal energy and chemical dosing. These would not deteriorate the quality of effluent before being reused or discharged to surface water.

However, the challenges are essential constraints, and the design should comply with the boundaries of construction and operations. An effective treatment would require adequate length size, below which alternate treatment or ex situ could be explored and implemented.

Overall Management Strategy

The complexities of managing in situ wastewater treatment for urban drains require a robust management strategy to ensure sustainability. Figure 6 provides a simple classification based on a drain’s outlet to either a river or another drain. In the former case, these are primary drains, while in the latter, these could form secondary or tertiary drains.

Fig. 6
figure 6

Classification of municipal drains as per the final point of discharge

The overall division could be kept simple regarding two types of treatment: the drain flows directly to a river source (or a drinking water source) and the other to a river basin or a higher-order drain, as depicted in Fig. 6. This step would ensure proper planning at the design stage. In addition to the segregation, Table 3 provides a decision implementation matrix for deciding on an appropriate treatment scheme. Table 3 suggests categorising drains considering the depth, flow and frequency of loading and final discharge source. This matrix could be extended for catering to different levels of dissolved oxygen and other pollutants magnitude.

Table 3 Sample decision implementation matrix for in situ wastewater treatment for urban drains

Table 3 would have to be sub-categorised into different levels such as A1, A2...An, where 1,2....n denotes variability in conditions of a particular drain. However, schemes could only be effective in multiple scenarios when all variables are considered in the design, thereby considerably reducing the number of design iterations required to manage drains.

Table 4 provides a suggested management framework involving different stakeholders for the suggested processes to perform effectively and efficiently.

Table 4: Suggested matrix of stakeholders’ roles and responsibilities


There are opportunities through schemes and systems, some requiring minimal energy without compromising efficiency, especially in shallow water depth. An example of this could be the use of biofilms which could either be natural or artificial. Steps coupled with emerging technologies such as bio-ropes (or bio-chords), which are low on chemical loading, where anaerobic and aerobic organisms can thrive, could effectively reduce pollutant loads. The other technologies which would follow similar characteristics could find applications in urban drains. Therefore, the following attributes can be safely assumed to present an excellent scope of in situ wastewater management and contribute to sustainability through a circular economy approach.

  • Availability of low-energy systems

  • Design of systems that can be efficient in shallow water depth and low flow

  • Systems for co-existence of anaerobic and aerobic organisms

  • Use of biofilms—natural and artificial

  • Exploring new technology such as Bio-ropes (or Bio-chords), algal-based solutions and others for cold weather conditions

  • In situ integration possibility

  • Low on chemical loading

Suggested Implementation Framework

Figure 7 provides a simple and basic technology framework for carrying out wastewater treatment in drains. The steps in the flow chart could include several other components and decision trees based on drain characteristics and other deciding parameters local to the selected drain. However, the decision steps should consist of the appropriate steps to ensure a practical design and engineering (Fig. 7). The framework should also consist of socio-political, economic and environmental considerations duly incorporated either at the feasibility state or the detailed project report.

Fig. 7
figure 7

Decision steps for wastewater management in drains

Circular Economy Approach

In the light of the present discussion concerning the feasibility of in situ wastewater treatment for municipal drains, it becomes imperative that planning and implementation of the treatment technologies follow a circular approach (Fig. 8). This philosophy would ensure maximum efficiency and recover beneficial nutrients and provide other services, including livelihood. The philosophy effectively would comprise of all phases from ensuring adequate checks and controls before wastewater discharge, proper treatment, recovering nutrients and utilising the solid and liquid fractions for suitable end-use applications. The creation of social, natural and economic capital could emerge from the proposed model depicted in Fig. 8.

Fig. 8
figure 8

Circular approach to wastewater management

The circular model proposed for achieving sustainability in urban or city drains consists of checking the inflow to the stormwater drain, controlling the pollutant load, treating pollutants, recovering nutrients and reusing the treated water or replenishing our water bodies with the treated water.

Future Research Scope

The deliberations covered in the paper lead to several opportunities for research and in-depth investigation. Some of these are as follows:

  • Performance evaluation of low cost and compact treatment systems for shallow depth

  • The efficiency of biofilms in different wastewater types along with seasonal variations

  • Optimising and standardising process sequence for municipal drains

  • Innovation for management of wastewater in anaerobic conditions (covered drains or partially covered drains)

  • The utilisation of decentralised bio-based systems, including algal systems [35] for treatment of drain wastewater

  • Maintenance of drains and sludge management

  • Use of AI and machine language for enhancement of wastewater quality monitoring and treatment thereof


Thebo et al. [36] indicated high utilisation of wastewater for irrigation, especially in India and four other countries through a GIS-based study. On the other hand, toxicity of rivers due to untreated wastewater from urban drains in and around the NCR has been established [37,38,39]. Several urban drains fall into rivers near rural settlements such as the Yamuna in Delhi and Ghaggar/Jhajjar in Haryana [40]. The untreated wastewater is toxic to human health and has rendered local agriculture unviable, causing significant crop losses and affecting the livelihood of farmers. Therefore, it becomes imperative that planners and urban local bodies consider a sound framework for in situ management of wastewater. A scientific approach would ensure that quality water suitable for crop plantation is available as per acceptable standards in rural areas.

The paper’s primary objective was to establish that nature-based or zero-energy in situ wastewater treatment systems are technically feasible for urban municipal drains that are or might have become sewers due to several geopolitical or other reasons. These could also be considered through the lens of circular economy and sustainability, despite several challenges. The paper dwells on the fact that with the advancement of science and technology, in situ treatment of wastewater is technically and economically viable in a decentralised manner.

Availability of Data and Material

The data and material utilised for this paper are part of an unpublished report undertaken by the CRDT, IIT Delhi, on management of municipal drains for North Delhi and South Delhi Municipal Corporations in 2020–2021.

Code Availability

Not applicable


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At the outset, the authors would like to thank the CRDT, IIT Delhi department for allowing to use the data and tables from the study, Action Plan on “Alternate Technology for Management of Wastewater in Drains” under the Jurisdiction of SDMC sponsored by the South Delhi Municipal Corporation (SDMC) and a similar one by North Delhi Municipal Corporation. Gratitude is extended to the organisers of the 1st International Conference Strategies toward Green Deal Implementation-Water and Raw Materials for providing a platform and opportunity for the presentation of this topic.

Special acknowledgements are due to Dr Rajesh B. Biniwale, Sr. Principal Scientist & Head, NEERI, who has inspired building the technical base of this paper and to Vivek Ramakrishna Jangde, Dy General Manager, Ecologique Science Technik (India) Private Limited, Nagpur, and team members of the abovementioned study for their timely suggestions and their encouragement.

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Correspondence to Vivek Kumar.

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Dasgupta, P., Kumar, V., Malik, A. et al. Wastewater Treatment Systems for City-Based Municipal Drains for Achieving Sustainability. Circ.Econ.Sust. (2022).

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  • Municipal drains
  • Sewage management
  • Circular economy
  • Treatment systems
  • Sustainability