Tanbir Khan - Academia.edu (original) (raw)

Papers by Tanbir Khan

Resilient and Responsible Smart Cities, 2022

Environmental Science and Pollution Research, 2021

This study reports organics and nutrient removal performances of the intensified constructed wetl... more This study reports organics and nutrient removal performances of the intensified constructed wetlands, i.e., tidal flow-based microbial fuel cell (MFC) and tidal flow wetlands that received municipal wastewater. The wetland systems were filled with organic (coco peat, biochar) or waste (Jhama brick, steel slag) materials, planted with Phragmites australis or Chrysopogon zizanioides (Vetiver) species, and operated under three flood periods: 8, 16, 24 h. Input ammonia nitrogen (NH3–N), total nitrogen (TN), phosphorus (P), chemical oxygen demand (COD), and biochemical oxygen demand (BOD) load across the wetland systems ranged between 3–27, 12–78, 0.1–23, 36–1130, and 11–281 g/m2day, respectively; mean removal percentages were 60–83, 74–84, 95–100, 94–98, and 93–97%, respectively, throughout the experimental run. The wetland systems achieved similar organics and P removals; operational and media variation did not influence removal kinetics. All wetland systems achieved the highest TN removal (76–87%) when subjected to 24-h flood period. TN removal performances of waste material–based wetlands were comparable to organic media-based systems. Tidal flow-based MFC wetlands achieved better TN removal than tidal flow wetlands because of supplementary electron production through fuel cell–based organics degradation kinetics. Maximum power production rates across the tidal flow-based MFC wetlands ranged between 53 and 57 mW/m2. Monod kinetics–based continuous stirred tank reactor (CSTR) models predicted NH3–N, TN, and COD removals (in wetland systems) more accurately. Kinetic models confirmed the influence of substrate (i.e., pollutant) and environmental parameters on pollutant removal routes.

Journal of Cleaner Production, 2021

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Environmental Science and Pollution Research, 2020

Constructed wetlands are low-cost, natural technologies that are often employed for the treatment... more Constructed wetlands are low-cost, natural technologies that are often employed for the treatment of different types of wastewater. In this study, landfill leachate and municipal wastewater were co-treated by the three parallel two-stage Phragmites-or Vetiver-based constructed wetland mesocosms. Two-stage wetland mesocosms included vertical flow (VF) units as the first stage, followed by horizontal flow (HF)/surface flow (SF)/floating treatment (FT) units. VF and HF wetland mesocosms were filled with gravel, steel slag, concrete block, and intermittent carbon-saturated ceramic filters as substrates. Mean input nitrogen, organics, and phosphorus load across first stages were 75 g N/m 2 day, 283 g COD/m 2 day, 88 g BOD/m 2 day, and 10 g P/ m 2 day, respectively. N and P accumulation rate was not substantial (< 10%) with respect to total removal in most wetland mesocosms. Gravel-based VF wetland mesocosm achieved better NH 4-N and BOD removal (55-59%) during landfill leachate treatment phase, when compared with co-treatment periods (12-52%). Slag-concrete-and ceramic filter-based VF wetland mesocosms maintained stable NH 4-N and BOD removals; the former wetland mesocosm was the most efficient VF unit (than other two wetland mesocosms) due to media characteristics. Media-based adsorption accelerated P removal (93%) in slagconcrete-based VF wetland mesocosm. Carbon scarcity limited denitrification in all VF wetland mesocosms; removal of TN was < 32%. Second stage wetland mesocosms achieved higher nitrogen (85-92%), organics (66-90%), and phosphorus (97-100%) removals regardless of operational variations; low input load, long retention time, media, and rhizosphere enhanced removal performances, particularly in HF and FT wetland mesocosms. In general, this study demonstrates potential application of two-stage wetland mesocosms for landfill leachate treatment or co-treatment with municipal sewage.

Chemical Engineering Journal, 2019

Abstract Six partially saturated and unsaturated tidal flow constructed wetlands (TFCWs) were stu... more Abstract Six partially saturated and unsaturated tidal flow constructed wetlands (TFCWs) were studied for the removal of nitrogen, phosphorus and organics from municipal wastewater. The TFCWs were packed with organic (biochar, coal, coco-peat), waste (slag), construction (gravel, concrete block) materials and planted with Phragmites or Vetiver. Daily wastewater feeding cycle was divided into sub-cycles across all TFCWs. Experimental analyses illustrated higher nitrogen and organics removals in organic media based TFCWs (71–85% and 84–96%, respectively), when compared with those of waste, construction material based units (49–69% and 74–95%, respectively); carbon availability from organic materials increased denitrification that was also supported by energy dispersive spectroscopy (EDS) analyses. Construction and waste material based TFCWs achieved better P removals (≥93%); Ca/Al/Fe ingredients of such materials allowed P removal via adsorption. Increment of wastewater contact period inside the media triggered physico-chemical and microbial removal routes. Partially saturated coal packed TFCW was the most efficient unit in terms of N removal percentage; presence of stationary water volume created anoxic environment and reduced input load, thereby improving removal performances. In terms of removal rates (g/m2 d), unsaturated TFCWs showed higher removal (over partially saturated units), which could be linked with greater input load. Mass balance analyses indicated ≤3% N removal through plant uptake; variation of plant species did not influence N removal. Therefore, observed removal kinetics was governed by adsorption and microbial routes. The results of this study suggest that, feeding sub-cycles could improve pollutant removals in TFCWs when packed with specific media.

Journal of Environmental Management, 2019

Two pilot scale wetland systems were studied for the removal of organics, nitrogen, phosphorus an... more Two pilot scale wetland systems were studied for the removal of organics, nitrogen, phosphorus and coliform from polluted surface water. Each system consisted of two units: a vertical flow (VF) wetland packed with construction materials gravel, brick or organic sugarcane bagasse, followed by a surface flow (SF) or floating treatment (FT) wetland. All wetland units were planted with Phragmites. The wetland systems were operated under constant and shock hydraulic load (HL) periods. Input COD, N, P loadings ranged between 61 and 2181, 7-1040, 2-194 g/m 2 d, respectively across first stages of each system. Mean removal percentages ranged between 39 and 97, 11-83, 20-100% and 4-85, 16-86, 1.4-100% across first and second stage wetlands, respectively. Mass balance analyses revealed ≤7% N and ≤14% P accumulation in plants; as such, microbial and adsorption kinetics controlled removal dynamics. Nitrification was the limiting nitrogen removal factor in first stage wetlands; organic carbon was supplied by the employed media. Aerobic organics removal and nitrification were diminished during initial stage of shock load periods. In contrast, second stage SF and FT wetlands showed stable removal performances under similar conditions. Resuspension of settled particles decreased removal performance in second stage wetlands, as shock periods progressed toward final stage. Coliform mortality was increased in second stage wetlands. Physico-chemical properties of brick materials in construction material based VF wetland and hanging root volume inside the water column of FT wetland supplemented removal performance. In general, this study provides evidence on potential application of constructed wetlands for polluted surface water treatment.

Chemical Engineering Journal, 2019

Three hybrid wetland systems were studied for organics and nutrients removal from synthetic waste... more Three hybrid wetland systems were studied for organics and nutrients removal from synthetic wastewater recipe. Each system included a vertical flow (VF) followed by a horizontal flow (HF) wetland. The wetlands were filled with common and unconventional media (gravel, biochar and sand) with different saturation and water depth ratio. Input N, P and COD loadings ranged between 48-145, 1-7 and 56-191 g/m 2 d, respectively across first stage VF wetlands. Recalcitrant compounds of synthetic recipe reduced organics removals in VF wetlands. NH 4-N adsorption and carbon leaching properties of biochar triggered N removals (19-102 g/m 2 d) in partially saturated VF wetlands. Carbon unavailability influenced N removals in gravel based unsaturated VF wetland. Input N load increment reduced nitrification and NH 4-N adsorption in VF wetlands. However, such increment improved N removal percentages in shallow water depth second stage HF wetlands, primarily due to removals in previous stages and atmospheric oxygen transfer via unsaturated zone; HF wetland with deep water depth showed opposite removal trend. P removal in experimental wetlands was achieved via media based adsorption; decrease of P concentration in synthetic recipe enhanced removals. N and P contents percentage (with respect to total removal) in plants ranged between 1-7% (VF), 5-17% (HF) and 2-36% (VF), 23-35% (HF), respectively, indicating dominance of microbial transformation and media based adsorption on observed removals. Partially saturated-shallow water depth hybrid wetland systems achieved ≥90% BOD, ≥ 97% N and 100% P removals. This study signifies potential application of partially saturated-shallow water depth hybrid wetland systems packed with unconventional media for wastewater treatment.

Resilient and Responsible Smart Cities, 2022

Environmental Science and Pollution Research, 2021

This study reports organics and nutrient removal performances of the intensified constructed wetl... more This study reports organics and nutrient removal performances of the intensified constructed wetlands, i.e., tidal flow-based microbial fuel cell (MFC) and tidal flow wetlands that received municipal wastewater. The wetland systems were filled with organic (coco peat, biochar) or waste (Jhama brick, steel slag) materials, planted with Phragmites australis or Chrysopogon zizanioides (Vetiver) species, and operated under three flood periods: 8, 16, 24 h. Input ammonia nitrogen (NH3–N), total nitrogen (TN), phosphorus (P), chemical oxygen demand (COD), and biochemical oxygen demand (BOD) load across the wetland systems ranged between 3–27, 12–78, 0.1–23, 36–1130, and 11–281 g/m2day, respectively; mean removal percentages were 60–83, 74–84, 95–100, 94–98, and 93–97%, respectively, throughout the experimental run. The wetland systems achieved similar organics and P removals; operational and media variation did not influence removal kinetics. All wetland systems achieved the highest TN removal (76–87%) when subjected to 24-h flood period. TN removal performances of waste material–based wetlands were comparable to organic media-based systems. Tidal flow-based MFC wetlands achieved better TN removal than tidal flow wetlands because of supplementary electron production through fuel cell–based organics degradation kinetics. Maximum power production rates across the tidal flow-based MFC wetlands ranged between 53 and 57 mW/m2. Monod kinetics–based continuous stirred tank reactor (CSTR) models predicted NH3–N, TN, and COD removals (in wetland systems) more accurately. Kinetic models confirmed the influence of substrate (i.e., pollutant) and environmental parameters on pollutant removal routes.

Journal of Cleaner Production, 2021

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Environmental Science and Pollution Research, 2020

Constructed wetlands are low-cost, natural technologies that are often employed for the treatment... more Constructed wetlands are low-cost, natural technologies that are often employed for the treatment of different types of wastewater. In this study, landfill leachate and municipal wastewater were co-treated by the three parallel two-stage Phragmites-or Vetiver-based constructed wetland mesocosms. Two-stage wetland mesocosms included vertical flow (VF) units as the first stage, followed by horizontal flow (HF)/surface flow (SF)/floating treatment (FT) units. VF and HF wetland mesocosms were filled with gravel, steel slag, concrete block, and intermittent carbon-saturated ceramic filters as substrates. Mean input nitrogen, organics, and phosphorus load across first stages were 75 g N/m 2 day, 283 g COD/m 2 day, 88 g BOD/m 2 day, and 10 g P/ m 2 day, respectively. N and P accumulation rate was not substantial (< 10%) with respect to total removal in most wetland mesocosms. Gravel-based VF wetland mesocosm achieved better NH 4-N and BOD removal (55-59%) during landfill leachate treatment phase, when compared with co-treatment periods (12-52%). Slag-concrete-and ceramic filter-based VF wetland mesocosms maintained stable NH 4-N and BOD removals; the former wetland mesocosm was the most efficient VF unit (than other two wetland mesocosms) due to media characteristics. Media-based adsorption accelerated P removal (93%) in slagconcrete-based VF wetland mesocosm. Carbon scarcity limited denitrification in all VF wetland mesocosms; removal of TN was < 32%. Second stage wetland mesocosms achieved higher nitrogen (85-92%), organics (66-90%), and phosphorus (97-100%) removals regardless of operational variations; low input load, long retention time, media, and rhizosphere enhanced removal performances, particularly in HF and FT wetland mesocosms. In general, this study demonstrates potential application of two-stage wetland mesocosms for landfill leachate treatment or co-treatment with municipal sewage.

Chemical Engineering Journal, 2019

Abstract Six partially saturated and unsaturated tidal flow constructed wetlands (TFCWs) were stu... more Abstract Six partially saturated and unsaturated tidal flow constructed wetlands (TFCWs) were studied for the removal of nitrogen, phosphorus and organics from municipal wastewater. The TFCWs were packed with organic (biochar, coal, coco-peat), waste (slag), construction (gravel, concrete block) materials and planted with Phragmites or Vetiver. Daily wastewater feeding cycle was divided into sub-cycles across all TFCWs. Experimental analyses illustrated higher nitrogen and organics removals in organic media based TFCWs (71–85% and 84–96%, respectively), when compared with those of waste, construction material based units (49–69% and 74–95%, respectively); carbon availability from organic materials increased denitrification that was also supported by energy dispersive spectroscopy (EDS) analyses. Construction and waste material based TFCWs achieved better P removals (≥93%); Ca/Al/Fe ingredients of such materials allowed P removal via adsorption. Increment of wastewater contact period inside the media triggered physico-chemical and microbial removal routes. Partially saturated coal packed TFCW was the most efficient unit in terms of N removal percentage; presence of stationary water volume created anoxic environment and reduced input load, thereby improving removal performances. In terms of removal rates (g/m2 d), unsaturated TFCWs showed higher removal (over partially saturated units), which could be linked with greater input load. Mass balance analyses indicated ≤3% N removal through plant uptake; variation of plant species did not influence N removal. Therefore, observed removal kinetics was governed by adsorption and microbial routes. The results of this study suggest that, feeding sub-cycles could improve pollutant removals in TFCWs when packed with specific media.

Journal of Environmental Management, 2019

Two pilot scale wetland systems were studied for the removal of organics, nitrogen, phosphorus an... more Two pilot scale wetland systems were studied for the removal of organics, nitrogen, phosphorus and coliform from polluted surface water. Each system consisted of two units: a vertical flow (VF) wetland packed with construction materials gravel, brick or organic sugarcane bagasse, followed by a surface flow (SF) or floating treatment (FT) wetland. All wetland units were planted with Phragmites. The wetland systems were operated under constant and shock hydraulic load (HL) periods. Input COD, N, P loadings ranged between 61 and 2181, 7-1040, 2-194 g/m 2 d, respectively across first stages of each system. Mean removal percentages ranged between 39 and 97, 11-83, 20-100% and 4-85, 16-86, 1.4-100% across first and second stage wetlands, respectively. Mass balance analyses revealed ≤7% N and ≤14% P accumulation in plants; as such, microbial and adsorption kinetics controlled removal dynamics. Nitrification was the limiting nitrogen removal factor in first stage wetlands; organic carbon was supplied by the employed media. Aerobic organics removal and nitrification were diminished during initial stage of shock load periods. In contrast, second stage SF and FT wetlands showed stable removal performances under similar conditions. Resuspension of settled particles decreased removal performance in second stage wetlands, as shock periods progressed toward final stage. Coliform mortality was increased in second stage wetlands. Physico-chemical properties of brick materials in construction material based VF wetland and hanging root volume inside the water column of FT wetland supplemented removal performance. In general, this study provides evidence on potential application of constructed wetlands for polluted surface water treatment.

Chemical Engineering Journal, 2019

Three hybrid wetland systems were studied for organics and nutrients removal from synthetic waste... more Three hybrid wetland systems were studied for organics and nutrients removal from synthetic wastewater recipe. Each system included a vertical flow (VF) followed by a horizontal flow (HF) wetland. The wetlands were filled with common and unconventional media (gravel, biochar and sand) with different saturation and water depth ratio. Input N, P and COD loadings ranged between 48-145, 1-7 and 56-191 g/m 2 d, respectively across first stage VF wetlands. Recalcitrant compounds of synthetic recipe reduced organics removals in VF wetlands. NH 4-N adsorption and carbon leaching properties of biochar triggered N removals (19-102 g/m 2 d) in partially saturated VF wetlands. Carbon unavailability influenced N removals in gravel based unsaturated VF wetland. Input N load increment reduced nitrification and NH 4-N adsorption in VF wetlands. However, such increment improved N removal percentages in shallow water depth second stage HF wetlands, primarily due to removals in previous stages and atmospheric oxygen transfer via unsaturated zone; HF wetland with deep water depth showed opposite removal trend. P removal in experimental wetlands was achieved via media based adsorption; decrease of P concentration in synthetic recipe enhanced removals. N and P contents percentage (with respect to total removal) in plants ranged between 1-7% (VF), 5-17% (HF) and 2-36% (VF), 23-35% (HF), respectively, indicating dominance of microbial transformation and media based adsorption on observed removals. Partially saturated-shallow water depth hybrid wetland systems achieved ≥90% BOD, ≥ 97% N and 100% P removals. This study signifies potential application of partially saturated-shallow water depth hybrid wetland systems packed with unconventional media for wastewater treatment.