Journal of Environmental Chemical Engineering, 2021
Abstract This study reports pollutant removal performance of two on-site wastewater treatment con... more Abstract This study reports pollutant removal performance of two on-site wastewater treatment configurations: a field-scale bioreactor septic tank that received wastewater generated from the washrooms of an educational institute, and a combined pilot-scale bioreactor septic tank, floating constructed wetland system dosed with municipal wastewater. Each bioreactor septic tank was divided into seven compartments: two settling chambers, two anaerobic baffle reactors (ABR), two stone media-packed biowalls, and an effluent collection chamber. Wastewater hydraulic retention time (HRT) in the field and pilot-scale bioreactor septic tanks were 24 and 72 h, respectively. Nitrogen (N), phosphorus (P), organic, and coliform removal percentage in the field-scale bioreactor septic tank were 56%, 76%, 84%, and 88%, respectively. The pilot-scale bioreactor septic tank achieved 93%, 100%, 99.6%, and 99.9% removal, respectively. Pollutant removal in different compartments of the bioreactor septic tanks was achieved through physical, chemical, and microbial degradation pathways. Greater HRT of wastewater in the pilot-scale bioreactor septic tank improved overall removal performance. The floating constructed wetland provided an additional treatment of the pilot-scale bioreactor septic tank effluent; the mean nitrogen and coliform removal percentage was 35% and 91%, respectively. The hanging root-zone (inside the water column) of the floating constructed wetland supported pollutant removal kinetics. This study demonstrates the potential application of the bioreactor septic tank for on-site wastewater treatment and integration of floating constructed wetland as a polishing stage.
M. Habibur Rahman (corresponding author) A. Al-Muyeed Department of Civil Engineering, Bangladesh... more M. Habibur Rahman (corresponding author) A. Al-Muyeed Department of Civil Engineering, Bangladesh University of Engineering and Technology, Dhaka, Bangladesh E-mail: habibr@ce.buet.ac.bd Arsenic contamination in the shallow aquifers has created the crisis and hence 4.73 million tubewells out of a total of 8.61million have been tested for arsenic contamination and 29% of these tested tubewells have been found to be contaminated with arsenic beyond the safe limit of Bangladesh standards. Around 81% of the inhabitants of our total villages are now affected with this poison where 27% of those are beyond the Bangladesh standards and which is responsible for the health suffering of 50million people. This paper examines this arsenic crisis and critically identifies treatment methods and technologies used for mitigation against this crisis. The common technologies that are used to treat arsenic-contaminated water are using oxidizing agents followed by flocculation and precipitation. Researc...
Sakhipur municipality with 32,000 inhabitants mostly comprise of onsite septic tank and pit toile... more Sakhipur municipality with 32,000 inhabitants mostly comprise of onsite septic tank and pit toilet of different types. When the pit or septic tank is full, the usual practice is to engage professional sweepers are employed to manually empty them and deposit the wastes in mostly the nearby water bodies. A co-compost plant was designed by the Sakhipur municipality and partners and it’s been in operation since 2016 to tackle faecal sludge generated from pit toilets and septic tanks, and solid waste from households exploring sanitation service chain. This study provides a description of an innovative co-composting system which improves current FSM practice in municipality regime. The generated lessons against tackling the operational challenges of sanitation service chain will provide good learnings for replicating similar practice in other municipalities.
Rapid urbanisation has exerted severe pressure on urban housing and public services in the metrop... more Rapid urbanisation has exerted severe pressure on urban housing and public services in the metropolitan city of Khulna, Bangladesh with which basic urban services could not cope. Situation coupled with the destitute economic condition of migrants has instigated the formation of large number of slums where service inadequacies on sanitation have been compounded and multiplied on a massive scale, resulting in hazardous environmental condition. Decentralized Wastewater Treatment System (DWTS) has recently gained much attention due to its build-as-you-go principle. This paper aims to examine and discuss the potential of a novel DWTS for urban development. The pilot DWTS was established in Panchtola colony located at Khalishpur, Khulna, Bangladesh. The paper first depicted how environmental sanitation of slum was improved with inclusion of ecotechnology. It was found that, overall removal efficiency of pollutants is more than 80% (COD, BOD5, PO4 and faecal bio-indicators) from influent.
This study summaries several monitoring and surveys on ambient concentrations of NOx, SO2, CO,O3 ... more This study summaries several monitoring and surveys on ambient concentrations of NOx, SO2, CO,O3 particulate matters, lead and black smoke which have been carried out by the authors, Bangladesh Atomic Energy Commission and Department of Environment (DOE) in Bangladesh. Airborne lead was a major concern but the phase-out of lead in gasoline implemented throughout South Asia in the year 1999 and the early 2000s has contributed greatly to reducing the lead concentration in ambient air. Analysis of the time series air quality data (of specific air pollutants, NOX, SO2, CO,O3 and particulate matters, for selected stations from the years 2002 to 2004) indicates that the ambient air of Dhaka City, the capital of Bangladesh, is polluted more than 55 percent of the year. The level of pollutants at 49 important road intersections shows the quality of air at the roadsides of Dhaka City. The air quality index (AQI) estimated at various locations of the city reveals that more than 70 percent of ...
... Final Report (Phase I), Department of Public Health Engineering (Bangladesh), Department for ... more ... Final Report (Phase I), Department of Public Health Engineering (Bangladesh), Department for International Development (UK) and British Geological Survey. January. DPHE and JICA (2008). Practice of Sustainable Arsenic Mitigation. ...
With the rapid development of communication and information technologies for the last few decades... more With the rapid development of communication and information technologies for the last few decades, the production of electrical instruments has increased. At the same time fast improvement of present technologies and intense marketing are engendering uncontrolled and unnecessary replacement of electrical instrument. Every year, 20 to 50 million tonnes of electrical and electronic equipment waste ("e-waste") are generated world-wide, which are sure to bring serious risks to human health and the environment, if not properly treated. E-waste usually contains hazardous materials such as lead, mercury, and hexavalent chromium which is highly hazardous for the environment. Televisions and CRT monitors contain four pounds of lead on average (the exact amount depends on size and make). Electronics have been cited as a leading source of mercury in municipal waste. There is a general lack of awareness by computer users and the public in general about the toxins contained in Informat...
This paper presents an overview of the current solid waste transfer system in Dhaka City and prov... more This paper presents an overview of the current solid waste transfer system in Dhaka City and provides an effective solution to overcome the present and future challenges in transporting waste. Optimal route including road network and water ways integrated with Geographic Information System (GIS) is critically assessed to determine the minimum distance efficient collection paths for transporting the solid wastes to the existing landfill sites. Introduction of waste transfer station near the river side and use of surrounding river route makes the proposed transport system more effective for waste hauling of Dhaka City Corporation (DCC). Waste dumping at the transfer stations decreases the haul time of the collection trucks 0.1h, 0.7h, 0.8h, 1 h per trip respectively for different DCC zones. From hydrographic survey data and field survey it is evident that the navigation facility of the river Buriganga is sufficient for waste transport using available water barge 1 .
This paper reports a comparative evaluation between two kinetic models for predicting nitrificati... more This paper reports a comparative evaluation between two kinetic models for predicting nitrification and biodegradable organics (BOD5) removal rates in five vertical flow (VF) wetland systems, that received strong wastewaters (i.e. tannery, textile and municipal effluents).The models were formulated by combining first order and Monod kinetics, with continuous-stirred tank reactor (CSTR) flow approach. The performance of the two models had been evaluated with three statistical parameters: coefficient of determination (R2), relative root mean square error (RRMSE), and model efficiency (ME). The statistical parameters indicated better performance of the Monod CSTR model (over first order CSTR approach), for correlating ammoniacal nitrogen (NH4-N), and BOD5 removal profiles across VF systems. Higher Monod coefficient values (from Monod CSTR model) coincided with greater input NH4-N, BOD5 loading, and experimentally measured removal rate (g/m2.d) values. Such trends indicate that NH4-N an...
[This is the published PhD thesis as Book by the University of Tokyo in 2008] The biochemistry an... more [This is the published PhD thesis as Book by the University of Tokyo in 2008] The biochemistry and microbiology of composting is still essentially considered a ‘black box’ process. This stems, in part, from the inherent complexity of the composting process, which is heterogeneous in nature and is directly influenced by factors such as feedstock composition and structure, and chemo-physical control parameters. This degradation process is accelerated through air flow inside the compost matrix. Hence, this research focuses first to identify the mechanisms of aerobic degradation in context of thermo-chemo-physical view. This incorporated knowledge in association with degradability of organic waste is targeted to implement in facilities development of large scale Self Turning Reactor (STR) composting system. And, in order to develop this sustainable large scale composting, it is necessary to incorporate the power of computational mathematics of composting process, which can improve under...
The solid waste in most of the urban centers in Bangladesh contains a very high proportion of bio... more The solid waste in most of the urban centers in Bangladesh contains a very high proportion of biodegradable organic fraction. The organic fraction of solid waste can be composted to reduce the volume of the waste and the compost can be used as soil conditioner. Hence the composting diverts the organic fraction of solid waste from municipal collection services and from final disposal site, and therefore, enhances both economic and environmental sustainability of waste management system. The use of compost as soil conditioner minimizes the use of chemical fertilizers, has significant environmental benefits. Thus the management of this organic fraction of solid waste is becoming a very important strategic option to minimize severe environmental pollution resulting from mismanagement of solid waste in many areas. The various environmental parameters of composting are observed during the aerobic digestion processes in different composting plants that have been presently operating in Bang...
Journal of Environmental Chemical Engineering, 2021
Abstract This study reports pollutant removal performance of two on-site wastewater treatment con... more Abstract This study reports pollutant removal performance of two on-site wastewater treatment configurations: a field-scale bioreactor septic tank that received wastewater generated from the washrooms of an educational institute, and a combined pilot-scale bioreactor septic tank, floating constructed wetland system dosed with municipal wastewater. Each bioreactor septic tank was divided into seven compartments: two settling chambers, two anaerobic baffle reactors (ABR), two stone media-packed biowalls, and an effluent collection chamber. Wastewater hydraulic retention time (HRT) in the field and pilot-scale bioreactor septic tanks were 24 and 72 h, respectively. Nitrogen (N), phosphorus (P), organic, and coliform removal percentage in the field-scale bioreactor septic tank were 56%, 76%, 84%, and 88%, respectively. The pilot-scale bioreactor septic tank achieved 93%, 100%, 99.6%, and 99.9% removal, respectively. Pollutant removal in different compartments of the bioreactor septic tanks was achieved through physical, chemical, and microbial degradation pathways. Greater HRT of wastewater in the pilot-scale bioreactor septic tank improved overall removal performance. The floating constructed wetland provided an additional treatment of the pilot-scale bioreactor septic tank effluent; the mean nitrogen and coliform removal percentage was 35% and 91%, respectively. The hanging root-zone (inside the water column) of the floating constructed wetland supported pollutant removal kinetics. This study demonstrates the potential application of the bioreactor septic tank for on-site wastewater treatment and integration of floating constructed wetland as a polishing stage.
M. Habibur Rahman (corresponding author) A. Al-Muyeed Department of Civil Engineering, Bangladesh... more M. Habibur Rahman (corresponding author) A. Al-Muyeed Department of Civil Engineering, Bangladesh University of Engineering and Technology, Dhaka, Bangladesh E-mail: habibr@ce.buet.ac.bd Arsenic contamination in the shallow aquifers has created the crisis and hence 4.73 million tubewells out of a total of 8.61million have been tested for arsenic contamination and 29% of these tested tubewells have been found to be contaminated with arsenic beyond the safe limit of Bangladesh standards. Around 81% of the inhabitants of our total villages are now affected with this poison where 27% of those are beyond the Bangladesh standards and which is responsible for the health suffering of 50million people. This paper examines this arsenic crisis and critically identifies treatment methods and technologies used for mitigation against this crisis. The common technologies that are used to treat arsenic-contaminated water are using oxidizing agents followed by flocculation and precipitation. Researc...
Sakhipur municipality with 32,000 inhabitants mostly comprise of onsite septic tank and pit toile... more Sakhipur municipality with 32,000 inhabitants mostly comprise of onsite septic tank and pit toilet of different types. When the pit or septic tank is full, the usual practice is to engage professional sweepers are employed to manually empty them and deposit the wastes in mostly the nearby water bodies. A co-compost plant was designed by the Sakhipur municipality and partners and it’s been in operation since 2016 to tackle faecal sludge generated from pit toilets and septic tanks, and solid waste from households exploring sanitation service chain. This study provides a description of an innovative co-composting system which improves current FSM practice in municipality regime. The generated lessons against tackling the operational challenges of sanitation service chain will provide good learnings for replicating similar practice in other municipalities.
Rapid urbanisation has exerted severe pressure on urban housing and public services in the metrop... more Rapid urbanisation has exerted severe pressure on urban housing and public services in the metropolitan city of Khulna, Bangladesh with which basic urban services could not cope. Situation coupled with the destitute economic condition of migrants has instigated the formation of large number of slums where service inadequacies on sanitation have been compounded and multiplied on a massive scale, resulting in hazardous environmental condition. Decentralized Wastewater Treatment System (DWTS) has recently gained much attention due to its build-as-you-go principle. This paper aims to examine and discuss the potential of a novel DWTS for urban development. The pilot DWTS was established in Panchtola colony located at Khalishpur, Khulna, Bangladesh. The paper first depicted how environmental sanitation of slum was improved with inclusion of ecotechnology. It was found that, overall removal efficiency of pollutants is more than 80% (COD, BOD5, PO4 and faecal bio-indicators) from influent.
This study summaries several monitoring and surveys on ambient concentrations of NOx, SO2, CO,O3 ... more This study summaries several monitoring and surveys on ambient concentrations of NOx, SO2, CO,O3 particulate matters, lead and black smoke which have been carried out by the authors, Bangladesh Atomic Energy Commission and Department of Environment (DOE) in Bangladesh. Airborne lead was a major concern but the phase-out of lead in gasoline implemented throughout South Asia in the year 1999 and the early 2000s has contributed greatly to reducing the lead concentration in ambient air. Analysis of the time series air quality data (of specific air pollutants, NOX, SO2, CO,O3 and particulate matters, for selected stations from the years 2002 to 2004) indicates that the ambient air of Dhaka City, the capital of Bangladesh, is polluted more than 55 percent of the year. The level of pollutants at 49 important road intersections shows the quality of air at the roadsides of Dhaka City. The air quality index (AQI) estimated at various locations of the city reveals that more than 70 percent of ...
... Final Report (Phase I), Department of Public Health Engineering (Bangladesh), Department for ... more ... Final Report (Phase I), Department of Public Health Engineering (Bangladesh), Department for International Development (UK) and British Geological Survey. January. DPHE and JICA (2008). Practice of Sustainable Arsenic Mitigation. ...
With the rapid development of communication and information technologies for the last few decades... more With the rapid development of communication and information technologies for the last few decades, the production of electrical instruments has increased. At the same time fast improvement of present technologies and intense marketing are engendering uncontrolled and unnecessary replacement of electrical instrument. Every year, 20 to 50 million tonnes of electrical and electronic equipment waste ("e-waste") are generated world-wide, which are sure to bring serious risks to human health and the environment, if not properly treated. E-waste usually contains hazardous materials such as lead, mercury, and hexavalent chromium which is highly hazardous for the environment. Televisions and CRT monitors contain four pounds of lead on average (the exact amount depends on size and make). Electronics have been cited as a leading source of mercury in municipal waste. There is a general lack of awareness by computer users and the public in general about the toxins contained in Informat...
This paper presents an overview of the current solid waste transfer system in Dhaka City and prov... more This paper presents an overview of the current solid waste transfer system in Dhaka City and provides an effective solution to overcome the present and future challenges in transporting waste. Optimal route including road network and water ways integrated with Geographic Information System (GIS) is critically assessed to determine the minimum distance efficient collection paths for transporting the solid wastes to the existing landfill sites. Introduction of waste transfer station near the river side and use of surrounding river route makes the proposed transport system more effective for waste hauling of Dhaka City Corporation (DCC). Waste dumping at the transfer stations decreases the haul time of the collection trucks 0.1h, 0.7h, 0.8h, 1 h per trip respectively for different DCC zones. From hydrographic survey data and field survey it is evident that the navigation facility of the river Buriganga is sufficient for waste transport using available water barge 1 .
This paper reports a comparative evaluation between two kinetic models for predicting nitrificati... more This paper reports a comparative evaluation between two kinetic models for predicting nitrification and biodegradable organics (BOD5) removal rates in five vertical flow (VF) wetland systems, that received strong wastewaters (i.e. tannery, textile and municipal effluents).The models were formulated by combining first order and Monod kinetics, with continuous-stirred tank reactor (CSTR) flow approach. The performance of the two models had been evaluated with three statistical parameters: coefficient of determination (R2), relative root mean square error (RRMSE), and model efficiency (ME). The statistical parameters indicated better performance of the Monod CSTR model (over first order CSTR approach), for correlating ammoniacal nitrogen (NH4-N), and BOD5 removal profiles across VF systems. Higher Monod coefficient values (from Monod CSTR model) coincided with greater input NH4-N, BOD5 loading, and experimentally measured removal rate (g/m2.d) values. Such trends indicate that NH4-N an...
[This is the published PhD thesis as Book by the University of Tokyo in 2008] The biochemistry an... more [This is the published PhD thesis as Book by the University of Tokyo in 2008] The biochemistry and microbiology of composting is still essentially considered a ‘black box’ process. This stems, in part, from the inherent complexity of the composting process, which is heterogeneous in nature and is directly influenced by factors such as feedstock composition and structure, and chemo-physical control parameters. This degradation process is accelerated through air flow inside the compost matrix. Hence, this research focuses first to identify the mechanisms of aerobic degradation in context of thermo-chemo-physical view. This incorporated knowledge in association with degradability of organic waste is targeted to implement in facilities development of large scale Self Turning Reactor (STR) composting system. And, in order to develop this sustainable large scale composting, it is necessary to incorporate the power of computational mathematics of composting process, which can improve under...
The solid waste in most of the urban centers in Bangladesh contains a very high proportion of bio... more The solid waste in most of the urban centers in Bangladesh contains a very high proportion of biodegradable organic fraction. The organic fraction of solid waste can be composted to reduce the volume of the waste and the compost can be used as soil conditioner. Hence the composting diverts the organic fraction of solid waste from municipal collection services and from final disposal site, and therefore, enhances both economic and environmental sustainability of waste management system. The use of compost as soil conditioner minimizes the use of chemical fertilizers, has significant environmental benefits. Thus the management of this organic fraction of solid waste is becoming a very important strategic option to minimize severe environmental pollution resulting from mismanagement of solid waste in many areas. The various environmental parameters of composting are observed during the aerobic digestion processes in different composting plants that have been presently operating in Bang...
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