Dinesh Kumar Poswal | IIT Bombay (original) (raw)
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Papers by Dinesh Kumar Poswal
Environmental Monitoring and Assessment, 2015
ABSTRACT Constructed wetlands (CW) are the engineered systems constituted of shallow impervious c... more ABSTRACT Constructed wetlands (CW) are the engineered systems constituted of shallow impervious concrete basin filled with highly pours media in which emergent wetland plants is being planted. CW are very prone to the problem of media clogging therefore, a good primary treatment is being given to wastewater before entering into the CW bed. There are number of treatment methods available that are being used for primary treatment to the wastewater. Septic Tank, Imhoff Tank, anaerobic digesters, lamella settler etc. are the most commonly used methods associated with primary treatment of wastewater before entering into CW bed. The most significant concern identified with long-term successful operation of CWs is if of clogging phenomenon. There are many contributing factors in clogging but the most significant one is due to of unrestrained suspended particle settling into the pore space of media – which carried through the raw wastewater. The primary treatment systems have been proven to be very significant in removal of suspended solids from wastewater considerably. Therefore, a good primary treatment always recommended to the tow wastewater before it enters into the CW bed. This paper reveals the literature associated with significance of primary treatment technology in enhancement of CW.
ABSTRACT The constructed wetlands (CWs), a lined basin containing media and wetland plants, treat... more ABSTRACT The constructed wetlands (CWs), a lined basin containing media and wetland plants, treats wastewater by a variety of physical, chemical, and biological means. The treatment of wastewater by nature-based technologies that utilize solar energy and living organisms has proven to be cost-effective as compared with energy-intensive and highly mechanized technologies for wastewater treatment. Currently, CWs are being utilized for removal of a range of pollutants and a broad variety of wastewaters worldwide. Horizontal subsurface constructed wetlands (HSF CWs) systems are the examples of the use of appropriate technology for the sanitation especially for small communities where the problem of power failure is common. This paper reveals the most common issues of clogging and lower phosphorus efficiency reported in HSF CWs. Paper also presents an attempt to integrate and reuse the information extracted from the literature and real experiences, to contribute to the prevention and solution of clogging problem and better phosphorus removal. The management of this information may also be allowed the proposal for successful operation and maintenance of constructed wetlands. The paper also concludes with some recommendations to overcome the clogging issue as well better phosphorus removal performance of HSF CW technology.
Journal of Scientific and Industrial Research, Mar 1, 2014
ABSTRACT Constructed wetlands (CWs) are becoming increasingly popular among natural treatment sys... more ABSTRACT Constructed wetlands (CWs) are becoming increasingly popular among natural treatment system (NTS) for onsite wastewater treatment due to their simplicity, low maintenance and installation cost. However, there are still some question marks regarding (i) how the treatment performance of CWs is affected by using different combinations plants and media for sewage treatment and (ii) What is the kinetics for uptake/degradation of pollutants for CWs using specific plants. This study investigated the removal efficiency of different kinds pollutants like, fecal bacteria, biological oxygen demand (BOD), and phosphorus and nitrogen removal from domestic wastewater using different wetland system.
This study assesses the long-term sustainability for operation and maintenance of sewage-fed aqua... more This study assesses the long-term sustainability for operation and maintenance of sewage-fed aquaculture based sewage treatment plant. The study focused on the integrated assessment of the engineered pond system of 8 million liter per day capacity in the city of Karnal, the State of Haryana, northern India. Major areas of analysis during the assessment included health, environmental, social and institutional aspects as well as the quality of treated effluent subjected for reuse. The treatment system met the Indian regulatory standards (for discharge of treated effluent for downstream reuse and discharge into water bodies) in terms of physico-chemical parameters throughout the year. The total coliform and faecal coliform removal was up to 2 -3 log units, however it was not able to meet the bacterial count requirements of <1000 per 100 mL to minimise human health risk in aquaculture practices. The system was able to generate sufficient profits required for routine O&M. The annual revenue collected by Municipal Corporation from the lease of the system as well as selling of treated wastewater was 3,077 USD and 16,667–25,000 USD, respectively. The additional benefit from the system for the farmers included the saving of fertilizers and cheaper source of water available for irrigation. The overall benefit for farmers by using the treated wastewater for cultivation of one acre of crop was estimated to be about 133 USD per year.
Paper summarizes the results of India-wide survey of natural treatment systems (NTSs) for wastewa... more Paper summarizes the results of India-wide
survey of natural treatment systems (NTSs) for
wastewater treatment and reuse. The quality of treated
wastewater from different types of NTSs was analyzed
for various physico-chemical and bacteriological parameters,
and needs for post-treatment were identified.
Currently, about 1838 million liters per day (MLD) of
wastewater is being treated using NTSs, of which the
contributions of polishing ponds, waste stabilization
ponds, duckweed ponds, constructed wetlands, and
Karnal technology were found to be 53.39, 45.15,
0.13, 0.55, and 0.78 %, respectively. Among the NTSs
studied, constructed wetland was found most efficient in
removal of pollutants including nitrogen, phosphorus,
total coliform, and fecal coliform in the range of 76, 61,
99.956, and 99.923 %, respectively. Of all types of
NTSs, only constructed wetland was found to meet the
total coliform count requirements (<1000 per 100 ml).
Of all the 108 NTSs in operation, 23 systems are producing
treated effluents for irrigation; effluents from 48
systems are being discharged into river or lake, and
remaining 38 systems have not found any designated
use of treated effluent. The chlorination was the only
post-treatment, which is being practiced at only three
wastewater treatment facilities. During post-treatment,
1–2 ppm of chlorine is applied to the secondary effluent
irrespective of its quality. The treated effluents from
different NTSs contain fecal bacteria in the magnitude
of 103 to 105, which may cause the severe health impacts
through contamination of groundwater as well as
surface water resources.
Water quality of drinking water sources and the distribution system of MNIT, Jaipur campus was co... more Water quality of drinking water sources and the distribution system of MNIT, Jaipur campus was
comprehensively studied for physical, chemical and bacteriological parameters as some incidences were
reported related to waterborne diseases. The results showed that all physical and chemical parameters were
within the limits but the biological parameters deviated from the prescribed standards of the BIS: 10500.
Bacteriological analysis was carried out using Colilert18 and cross checked by the standard pour plate
method. Results obtained after pour plating method showed the presence of 33% Serratia, 33% Citrobacter,
18% Klebsiella, and 18% Enterobacter among the pathogens analysed in the most contaminated sample
obtained from a residential apartment of the campus. Presence of high level of bacterial count in drinking
water indicates the contamination of drinking water distribution system by sewage. In light of these findings,
appropriate remedial measures were taken by the authorities supplying water to the campus in terms of
cleaning of sewer lines and refurbishing of tube wells followed by regular disinfection of drinking supplies.
After the refurbishment, bacteriological test results of water samples collected from various locations covering
the entire campus revealed complete absence of coliforms representing a good quality of water.
The present study reports the efficiency of chlorine disinfection on secondary treated sewage. Th... more The present study reports the efficiency of chlorine
disinfection on secondary treated sewage. The disinfectant used was
calcium hypochlorite and bacteria were counted by spread plate
cultures and colilert 18hr method with Quant-trays. Six genera
Escherichia, Klebsiella, Enterobacter, Pseudomonas, Hafnia and
Citrobacter were considered for this study because they comprised 95 %
of total coliform population in the initial screening. Results shows that,
two log reductions were observed for most of the species in the first 5
minutes of contact time(CT) at every chlorine dose(CD). The
subsequent 10 minutes were not found to be very effective. The period
of 15-20 minutes of contact was again found effective for disinfection
underlying the importance of delayed disinfection due to the combined
forms. A dose of 17.5 ppm in the form of calcium hypochlorite was
found to be optimum for disinfection because this was the minimum
dose required to bring the total coliform and pathogenic counts to less
than 1000 per 100 ml, which are the desired USEPA standards
(USEPA).
High population growth, increasing urbanization and rapid economic development are exerting press... more High population growth, increasing urbanization and rapid economic development are exerting pressure on the already scarce water resources in India. Untreated wastewater from human settlements reaching natural waterways is very common contributing to environmental pollution, which directly affects the availability of fresh water for human consumption. Therefore, treatment and reuse of wastewater can play an important role in addressing some of the urban water challenges in India. Conventional treatment plants have many challenges, therefore, natural treatment systems are viewed as a cost-effective alternative, which are more suitable in the Indian context. For example, they are not reliant on electricity, easier to maintain, can be part of small decentralised systems and work well in tropical climates. This study presents a rapid sustainability assessment and a review of the potential of natural treatment systems in India. The preliminary results show that the natural treatment systems have a high potential for wastewater treatment. However, there are still gaps in knowledge related to aspects that hinder the sustainable functioning of these treatment systems.
Bacterial testing kits are designed to provide rapid and cost-effective solutions for testing the... more Bacterial testing kits are designed to provide rapid and cost-effective solutions for testing the
bacterial contamination in potable water with reasonable accuracy. In this study, the culture method
of bacteriological examination was used to critically evaluate the sensitivity of three different
bacteriological test methods, namely, Colilert-18h method, H2S Test Medium (Powder) K019 and
Bacteriological H2S Strip Test, to provide an appropriate end-point use. Bacteriological sensitivity
results of Colilert-18h were compared with those of the culture method. Once the Colilert-18h was
found to be very sensitive to total coliform counts (TCC), the sensitivity analysis of the other two field
kits was carried out. Results obtained from Colilert-18h showed that it is a highly sensitive and
reproducible method as corroborated by the results of the spread plating method. Subsequently, the
Colilert-18h method was used as a standard for critically evaluating the sensitivity of two available
field kits, namely, H2S Test Medium (Powder) K019 (sensitive for 4 TCC) and Bacteriological H2S
Strip Test (sensitive for 30 TCC) within 24–48 h of incubation, as suggested in their procedures.
Thus, H2S Test Medium (Powder) K019 is recommended for routine field testing for coliforms, as it is
able to detect Salmonella, Citrobacter and other bacteria simultaneously.
Environmental Monitoring and Assessment, 2015
ABSTRACT Constructed wetlands (CW) are the engineered systems constituted of shallow impervious c... more ABSTRACT Constructed wetlands (CW) are the engineered systems constituted of shallow impervious concrete basin filled with highly pours media in which emergent wetland plants is being planted. CW are very prone to the problem of media clogging therefore, a good primary treatment is being given to wastewater before entering into the CW bed. There are number of treatment methods available that are being used for primary treatment to the wastewater. Septic Tank, Imhoff Tank, anaerobic digesters, lamella settler etc. are the most commonly used methods associated with primary treatment of wastewater before entering into CW bed. The most significant concern identified with long-term successful operation of CWs is if of clogging phenomenon. There are many contributing factors in clogging but the most significant one is due to of unrestrained suspended particle settling into the pore space of media – which carried through the raw wastewater. The primary treatment systems have been proven to be very significant in removal of suspended solids from wastewater considerably. Therefore, a good primary treatment always recommended to the tow wastewater before it enters into the CW bed. This paper reveals the literature associated with significance of primary treatment technology in enhancement of CW.
ABSTRACT The constructed wetlands (CWs), a lined basin containing media and wetland plants, treat... more ABSTRACT The constructed wetlands (CWs), a lined basin containing media and wetland plants, treats wastewater by a variety of physical, chemical, and biological means. The treatment of wastewater by nature-based technologies that utilize solar energy and living organisms has proven to be cost-effective as compared with energy-intensive and highly mechanized technologies for wastewater treatment. Currently, CWs are being utilized for removal of a range of pollutants and a broad variety of wastewaters worldwide. Horizontal subsurface constructed wetlands (HSF CWs) systems are the examples of the use of appropriate technology for the sanitation especially for small communities where the problem of power failure is common. This paper reveals the most common issues of clogging and lower phosphorus efficiency reported in HSF CWs. Paper also presents an attempt to integrate and reuse the information extracted from the literature and real experiences, to contribute to the prevention and solution of clogging problem and better phosphorus removal. The management of this information may also be allowed the proposal for successful operation and maintenance of constructed wetlands. The paper also concludes with some recommendations to overcome the clogging issue as well better phosphorus removal performance of HSF CW technology.
Journal of Scientific and Industrial Research, Mar 1, 2014
ABSTRACT Constructed wetlands (CWs) are becoming increasingly popular among natural treatment sys... more ABSTRACT Constructed wetlands (CWs) are becoming increasingly popular among natural treatment system (NTS) for onsite wastewater treatment due to their simplicity, low maintenance and installation cost. However, there are still some question marks regarding (i) how the treatment performance of CWs is affected by using different combinations plants and media for sewage treatment and (ii) What is the kinetics for uptake/degradation of pollutants for CWs using specific plants. This study investigated the removal efficiency of different kinds pollutants like, fecal bacteria, biological oxygen demand (BOD), and phosphorus and nitrogen removal from domestic wastewater using different wetland system.
This study assesses the long-term sustainability for operation and maintenance of sewage-fed aqua... more This study assesses the long-term sustainability for operation and maintenance of sewage-fed aquaculture based sewage treatment plant. The study focused on the integrated assessment of the engineered pond system of 8 million liter per day capacity in the city of Karnal, the State of Haryana, northern India. Major areas of analysis during the assessment included health, environmental, social and institutional aspects as well as the quality of treated effluent subjected for reuse. The treatment system met the Indian regulatory standards (for discharge of treated effluent for downstream reuse and discharge into water bodies) in terms of physico-chemical parameters throughout the year. The total coliform and faecal coliform removal was up to 2 -3 log units, however it was not able to meet the bacterial count requirements of <1000 per 100 mL to minimise human health risk in aquaculture practices. The system was able to generate sufficient profits required for routine O&M. The annual revenue collected by Municipal Corporation from the lease of the system as well as selling of treated wastewater was 3,077 USD and 16,667–25,000 USD, respectively. The additional benefit from the system for the farmers included the saving of fertilizers and cheaper source of water available for irrigation. The overall benefit for farmers by using the treated wastewater for cultivation of one acre of crop was estimated to be about 133 USD per year.
Paper summarizes the results of India-wide survey of natural treatment systems (NTSs) for wastewa... more Paper summarizes the results of India-wide
survey of natural treatment systems (NTSs) for
wastewater treatment and reuse. The quality of treated
wastewater from different types of NTSs was analyzed
for various physico-chemical and bacteriological parameters,
and needs for post-treatment were identified.
Currently, about 1838 million liters per day (MLD) of
wastewater is being treated using NTSs, of which the
contributions of polishing ponds, waste stabilization
ponds, duckweed ponds, constructed wetlands, and
Karnal technology were found to be 53.39, 45.15,
0.13, 0.55, and 0.78 %, respectively. Among the NTSs
studied, constructed wetland was found most efficient in
removal of pollutants including nitrogen, phosphorus,
total coliform, and fecal coliform in the range of 76, 61,
99.956, and 99.923 %, respectively. Of all types of
NTSs, only constructed wetland was found to meet the
total coliform count requirements (<1000 per 100 ml).
Of all the 108 NTSs in operation, 23 systems are producing
treated effluents for irrigation; effluents from 48
systems are being discharged into river or lake, and
remaining 38 systems have not found any designated
use of treated effluent. The chlorination was the only
post-treatment, which is being practiced at only three
wastewater treatment facilities. During post-treatment,
1–2 ppm of chlorine is applied to the secondary effluent
irrespective of its quality. The treated effluents from
different NTSs contain fecal bacteria in the magnitude
of 103 to 105, which may cause the severe health impacts
through contamination of groundwater as well as
surface water resources.
Water quality of drinking water sources and the distribution system of MNIT, Jaipur campus was co... more Water quality of drinking water sources and the distribution system of MNIT, Jaipur campus was
comprehensively studied for physical, chemical and bacteriological parameters as some incidences were
reported related to waterborne diseases. The results showed that all physical and chemical parameters were
within the limits but the biological parameters deviated from the prescribed standards of the BIS: 10500.
Bacteriological analysis was carried out using Colilert18 and cross checked by the standard pour plate
method. Results obtained after pour plating method showed the presence of 33% Serratia, 33% Citrobacter,
18% Klebsiella, and 18% Enterobacter among the pathogens analysed in the most contaminated sample
obtained from a residential apartment of the campus. Presence of high level of bacterial count in drinking
water indicates the contamination of drinking water distribution system by sewage. In light of these findings,
appropriate remedial measures were taken by the authorities supplying water to the campus in terms of
cleaning of sewer lines and refurbishing of tube wells followed by regular disinfection of drinking supplies.
After the refurbishment, bacteriological test results of water samples collected from various locations covering
the entire campus revealed complete absence of coliforms representing a good quality of water.
The present study reports the efficiency of chlorine disinfection on secondary treated sewage. Th... more The present study reports the efficiency of chlorine
disinfection on secondary treated sewage. The disinfectant used was
calcium hypochlorite and bacteria were counted by spread plate
cultures and colilert 18hr method with Quant-trays. Six genera
Escherichia, Klebsiella, Enterobacter, Pseudomonas, Hafnia and
Citrobacter were considered for this study because they comprised 95 %
of total coliform population in the initial screening. Results shows that,
two log reductions were observed for most of the species in the first 5
minutes of contact time(CT) at every chlorine dose(CD). The
subsequent 10 minutes were not found to be very effective. The period
of 15-20 minutes of contact was again found effective for disinfection
underlying the importance of delayed disinfection due to the combined
forms. A dose of 17.5 ppm in the form of calcium hypochlorite was
found to be optimum for disinfection because this was the minimum
dose required to bring the total coliform and pathogenic counts to less
than 1000 per 100 ml, which are the desired USEPA standards
(USEPA).
High population growth, increasing urbanization and rapid economic development are exerting press... more High population growth, increasing urbanization and rapid economic development are exerting pressure on the already scarce water resources in India. Untreated wastewater from human settlements reaching natural waterways is very common contributing to environmental pollution, which directly affects the availability of fresh water for human consumption. Therefore, treatment and reuse of wastewater can play an important role in addressing some of the urban water challenges in India. Conventional treatment plants have many challenges, therefore, natural treatment systems are viewed as a cost-effective alternative, which are more suitable in the Indian context. For example, they are not reliant on electricity, easier to maintain, can be part of small decentralised systems and work well in tropical climates. This study presents a rapid sustainability assessment and a review of the potential of natural treatment systems in India. The preliminary results show that the natural treatment systems have a high potential for wastewater treatment. However, there are still gaps in knowledge related to aspects that hinder the sustainable functioning of these treatment systems.
Bacterial testing kits are designed to provide rapid and cost-effective solutions for testing the... more Bacterial testing kits are designed to provide rapid and cost-effective solutions for testing the
bacterial contamination in potable water with reasonable accuracy. In this study, the culture method
of bacteriological examination was used to critically evaluate the sensitivity of three different
bacteriological test methods, namely, Colilert-18h method, H2S Test Medium (Powder) K019 and
Bacteriological H2S Strip Test, to provide an appropriate end-point use. Bacteriological sensitivity
results of Colilert-18h were compared with those of the culture method. Once the Colilert-18h was
found to be very sensitive to total coliform counts (TCC), the sensitivity analysis of the other two field
kits was carried out. Results obtained from Colilert-18h showed that it is a highly sensitive and
reproducible method as corroborated by the results of the spread plating method. Subsequently, the
Colilert-18h method was used as a standard for critically evaluating the sensitivity of two available
field kits, namely, H2S Test Medium (Powder) K019 (sensitive for 4 TCC) and Bacteriological H2S
Strip Test (sensitive for 30 TCC) within 24–48 h of incubation, as suggested in their procedures.
Thus, H2S Test Medium (Powder) K019 is recommended for routine field testing for coliforms, as it is
able to detect Salmonella, Citrobacter and other bacteria simultaneously.