Atul K. Mittal

Efficiency evaluation of sewage treatment plants with different technologies in Delhi (India).

Physical, chemical and microbiological efficiencies of Sewage Treatment Plants (STPs) located in Delhi’s watershed in context of different treatment technologies employed in these plants have been determined. There were in all seventeen STPs treating domestic wastewater which were studied over a period of 12 months. These STPs were based on Conventional Activated sludge process (ASP), Extended aeration (Ex. Aeration), physical, chemical and biological removal treatment (BIOFORE) and oxidation pond treatment process. Results suggests that except “Mehrauli” STP which was based on Extended aeration process and “Oxidation pond”, effluents from all other STPs exceeded FC standard of 103 MPN/100 ml for unrestricted irrigation criteria set by National river conservation directorate (NRCD). Actual integrated efficiency (IEa) of each STP was evaluated and compared with the standard integrated efficiency (IEs) based upon physical, biological and microbiological removal efficiencies depending upon influent sewage characteristics. The best results were obtained for STPs employing extended aeration, BIOFORE and oxidation pond treatment process thus can be safely used for irrigation purposes.

Occurrences and fate of an antibiotic amoxicillin in extended aeration-based sewage treatment plant in Delhi, India: a case study of emerging pollutant

Abstract In recent years, pharmaceutical and personal care products (PPCPs) have been detected in various environmental matrices, including ground water, surface water, and municipal wastewater. In order to evaluate the impact of PPCPs on environment, their distribution must be accurately established in these matrices first, as very limited studies have been carried out especially in the Indian subcontinent. In this study, the occurrence and removal of an antibiotic, Amoxicillin, at a sewage treatment plant (STP) located in Delhi has been studied. Amoxicillin was selected for its widespread use as a prescribed over the counter drug. Sampling exercises were carried out over a period of six months so as to cover seasonal variations. Sewage samples were collected from the influents and effluents of STP to determine the occurrences and removal of the amoxicillin. Concentration of amoxicillin in the untreated raw sewage at the STP varied from “not detected” (ND) to 172.6 ng L−1. After treatment, it varied from...

Benchmarking of North Indian urban water utilities

Purpose – The purpose of this paper is to develop a suitable benchmarking framework that encompasses multiple criteria of sustainable water supply services for assessing the performance of select North Indian urban water utilities and also to arrive at potential for input reductions (or efficient input levels).Design/methodology/approach – The study considers 35 North Indian urban water utilities pertaining to two union territories (Chandigarh and Delhi) and three states (Haryana, Punjab and Uttar Pradesh) for sustainability‐based performance assessment using input‐oriented variable returns to scale data envelopment analysis (DEA) model. Important criteria considered for sustainable water supply services are service sufficiency, service reliability, resource conservation, staff rationalization, and business viability which in turn address the key sustainability dimensions (social, environmental and financial).Findings – The approach when applied to a sample of 35 North Indian urban water utilities shows l...

Effects of urbanisation on the quality of the urban runoff for Delhi watershed

The current paper is the first study to report quality of urban runoff, focusing on the diffuse sources contributing to pollutant loads in the Delhi watershed. The quality of stormwater runoff from the urban watershed of Delhi was evaluated to assess the effects of different land-use practices on pollutant concentrations. Six sites within the Delhi watershed with different land-use characteristics were selected. The microbial quality of the urban runoff from sub-catchments of Delhi watershed is very poor with Faecal Coliform (FC) levels varying between 6 and 7 log orders. There was a good correlation between the chemical and biological quality of urban runoff with land-use characteristics such as impervious land and population density. Except for chemical oxygen demand all other parameters in urban runoff were found to exceed the effluent discharge standards set by the National River Conservation Directorate (NRCD), India. The public health risks associated with exposure to urban runoff via different routes have also been qualitatively estimated.

Applicability of immobilized wood-rotting fungal biomass for biosorption of basic dye Alcian Blue.

In this study potential applicability of immobilised biomass of a wood-rotting dead macro-fungus Fomitopsis carnea are explored for the removal of the basic dye Alcian Blue. Effect of several parameters viz., temperature, pH and salt were studied in batch mode. In view of reutilization of the dye as well as the biosorbent, desorption/regeneration experiments were conducted. Desorption/regeneration studies could also be helpful in determining dye sorption mechanism. Studies indicate that the immobilized biosorbent could remove Alcian Blue efficiently. The experimental equilibrium data were modeled using the Langmuir equation. Dye uptake capacity of the biosorbent was observed to increase with rise in temperature and indicates chemisorption and/or ion exchange. The uptake was 11.1, 13.2, 16.4 and 24.2 mg/g at 10, 20, 30 and 40 degrees C respectively. Higher removal of dye was also observed at higher pH. However, increased salt concentration from 0 mmol/L to 100 mmol/L reduced from 89 to 85%. Desorption of dye could be possible up to 51% using 0.1 M hydrochloric/acetic acids and thus suggests that ion-exchange and chemisorption could be the possible dye sorption mechanism.

Characterization of biofilm of a rotating biological contactor treating synthetic wastewater.

A four-stage rotating biological contactor (RBC) was designed and operated to treat synthetic wastewater containing 1,000 mg/l chemical oxygen demand (COD) and 112 mg/l NH(4)(+)-N. A mixed culture bacterial biofilm was developed consisting of a heterotrophic bacterium Paracoccus pantotrophus, nitrifiers and other heterotrophs. Applying the peculiar characteristics of P. pantotrophus of simultaneous heterotrophic nitrification and aerobic denitrification, high simultaneous removal of carbon and nitrogen could be achieved in the fully aerobic RBC. The microbial community structure of the RBC biofilm was categorized based on the nitrate reduction, biochemical reactions, gram staining and morphology. The presence of P. pantotrophus within the RBC biofilm was confirmed with an array of biochemical tests. Isolates from the four stages of RBC were grouped into complete denitrifiers, incomplete denitrifiers and non-denitrifiers. This categorization showed a higher relative abundance of P. pantotrophus in the first stage as compared with subsequent stages, in which other nitrifiers and heterotrophs were significantly present. High total nitrogen removal of upto 68% was in conformity with observations made using microbial categorization and biochemical tests. The high relative abundance of P. pantotrophus in the biofilm revealed that it could successfully compete with other heterotrophs and autotrophic nitrifiers in mixed bacterial biomass.

Integrated biological and advanced oxidation based treatment of hexamine bearing wastewater: Effect of cow-dung as a co-substrate

This work examines the treatment of hexamethylenetetramine (HMT) bearing effluent from N, N-dinitroso pentamethylene tetra-mine producing industrial plants in India. Chemical treatment using Fentons reagent and aerobic treatment using batch reactors with co-substrate were investigated. Aerobic batch reactors integrated with advanced oxidation process of Fentons reagent provides effective treatment of HMT effluents. Influence of Fentons reagent dose reaction/contact and effect of varying co-substrate with effluent initial concentration was observed. Higher dose 100 mL of Fentons reagent with higher reaction time 20 h resulted better degradation (34.88%) of wastewater. HMT hydrolyzes in acidic environment to ammonia and formaldehyde. Formaldehyde under normal conditions is toxic for biological treatment processes. When hydrolysis and acidification in the reactors are accompanied by low pH, aerobic batch reactors with use of co-substrates glucose, sucrose, and cow-dung extract separately in different proportion to wastewater ranging from 0.67 to 4.00, degraded wastewater effectively. Higher proportion of co-substrate to wastewater resulted better degradation. The relationships between nitrate, pH, turbidity and COD are discussed.

Performance aspects of Paracoccus pantotrophus treating urban solid waste leachate

Abstract Municipal landfill leachate remains one of the most challenging substrates to be biologically processed. This is the first study to report the behaviour of a mixotrophic bacterium Paracoccus pantotrophus which can simultaneously remove carbon and nitrogen. Both synthetic media and leachate have been used as substrate. Different leachate fractions, i.e. 0, 10, 20, 30, 40 and 50% were investigated. Total initial COD was 1,000 mg/L, which was reduced to 106–204 mg/L as leachate fraction varied from 0 to 50%. Removal of nitrogen was 20–38%. Inhibitory effects of the leachate on the microbial growth and substrate utilization were observed from the maximum microbial growth and sustenance of the biomass. Sustenance of the biomass which was estimated using duration of the stationary phase varied from 124 to 25 h as leachate fraction varied from 0 to 50%. COD levels in all the reactors containing leachate started to increase after 150 h. Such increase continually increased with higher leachate fractions. ...

Treatment of Urban Run Off Using Constructed Wetlands in New Delhi, India

The River Yamuna forms an integral part of the Indo-Gangetic plains. Delhi, capital of India, constitutes only 2% of the entire catchment area of the River Yamuna. The pollution problem posed by urban wastewater discharges from open storm drains owes its origins to the inadequate development of sewerage systems in the city, coupled with sharp increases in population stemming from the industrial revolution. Early approaches to mitigate pollution load in river under Yamuna Action Plan (YAP) were focused on the treatment of domestic as well as industrial wastewater, whereas the issue of urban runoff remained completely untouched. The present research is directed at the development of constructed wetlands, in order to achieve an optimal solution to the requirement to treat sewage (treated as well as untreated) and urban runoff whilst meeting environmental requirements of the receiving water. The availability of land was a problem on the banks where the drain meets the river; hence a methodology is proposed to transfer the drain water by means of aqueducts to the opposite bank, where there is availability of unused floodplains of the river. For the entire treatment setup it is found that even though initial investment required is huge but the running and maintenance cost is very low as compared to conventional sewage treatment plants. It is concluded that if implemented correctly these wetlands would not only provide an ideal solution to help curb the problem of pollution but also create a healthy natural ecosystem near the riverbanks.

Toxicity and treatability of leachate: application of UASB reactor for leachate treatment from Okhla landfill, New Delhi.

This study reports applicability of upflow anaerobic sludge blanket (UASB) process to treat the leachate from a municipal landfill located in Delhi. A laboratory scale reactor was operated at an organic loading rate of 3.00 kg chemical oxygen demand (COD)/m(3) d corresponding to a hydraulic retention time (HRT) of 12 h for over 8 months. The effect of toxicity of leachate, and feed composition on the treatability of leachate was evaluated. Average COD of the leachate, during the study period varied between 8,880 and 66,420 mg/l. Toxicity of the leachate used during a period of 8 months varied from LC50 1.22 to 12.35 for 96 h. The removal efficiency of soluble COD ranged between 91 and 67% for fresh leachate and decreased drastically from 90 to 35% for old leachate having high toxicity. The efficiency varied from 81 to 65%. The reactor performed more efficiently for the treatment of fresh leachate (less toxic, LC50 11.64, 12.35, and 12.15 for 96 h) as compared with old leachate (more toxic, LC50 1.22 for 96 h). Toxicity of the leachate affected its treatment potential by the UASB.