scholarly journals Potential Nitrate Reduction Rates in Marine Mangrove Sediments in the Lesser Antilles

2021 ◽  
Author(s):  
anniet laverman ◽  
Mathieu Sebilo ◽  
Jennifer Tocny ◽  
Olivier Gros
Keyword(s):  
Organic Carbon ◽  
Retention Time ◽  
Nitrate Reduction ◽  
Hydraulic Retention Time ◽  
Nitrogen Retention ◽  
Fold Increase ◽  
Anthropogenic Activity ◽  
Mangrove Sediments ◽  
Nitrogen Elimination ◽  
The Impact

Abstract Mangrove sediments are generally nitrogen limited, with nitrate reduction to ammonium instead of denitrification in these sediments, resulting in nitrogen retention rather than nitrogen elimination. The goal of this work was to investigate the potential for nitrate reduction in marine mangrove sediments along a canal impacted by anthropogenic activity (Guadeloupe, West Indies) as a function of increased nitrogen load and how this would change nitrate transformation rates. In addition to that, the impact of the organic carbon load and the hydraulic retention time was assessed as factors affecting nitrate reduction rates. Potential nitrate reduction rates in the sediments along the canal, in the presence of indigenous organic carbon, ranged from 126 to 379 nmol cm‑3 h-1 generally increasing upon increasing supplied nitrate. The potential for nitrate reduction increased significantly with the addition of mangrove leaves, whereas the addition of simple, easily degradable carbon (acetate), resulted in an almost five-fold increase in nitrate reduction rates. The hydraulic retention time also had an impact on the nitrate reducing capacity due to an increased contact time between nitrate and the benthic microbial community. Marine mangrove sediments have a high potential to mitigate nitrogen pollution, mainly governed by the presence of large amounts of degradable carbon in the form of litter. The hydraulic retention time as tested experimentally that can be extrapolated to the time of inundation of the mangrove sediments may increase the potential for nitrate reduction. Whereas the sediments are daily exposed to a small tidal effect, increased water retention could increase the nitrogen elimination potential in these mangrove sediments.

Two-Phase Mesophilic Anaerobic Co-Digestion of Food Waste and Sewage Sludge: Effect of Hydraulic Retention Time

2014 ◽  
Vol 852 ◽  
pp. 789-796 ◽  
Author(s):  
Guo Hua Wang ◽  
Lei Wang ◽  
Xue Jun Tan ◽  
Yi Xian Wang ◽  
Feng Wang
Keyword(s):  
Anaerobic Digestion ◽  
Sewage Sludge ◽  
Food Waste ◽  
Retention Time ◽  
Hydraulic Retention Time ◽  
Removal Rate ◽  
Two Phase ◽  
Acidogenic Reactor ◽  
In Series ◽  
The Impact

The impact of hydraulic retention time (HRT) on two-phase mesophilic (35°C) anaerobic co-digestion of food waste and sewage sludge was studied under mixing ratio of 1:1 on the TS basis. Laboratory-scale, two-phase anaerobic digestion systems were employed with each system consisting of an acidogenic reactor and a methanogenic reactor linked in series. For the acidogenic phase, an increase of volatile fatty acid (VFA) concentration was observed as HRT increased from 1d to 5d and the HRT of 5d was recommended for significantly higher VFA production and less propionate percentage, which could provide stable and favourable substrates for the methane reactor. Under acidogenic HRT of 5d, 20d was proved to be the optimum HRT for methanogenic phase with the methane content, methane production rate, methane yield and two-phase VS removal rate reached 71%, 0.7L/(L·d), 0.69L/gVSremoved and 64.7%, respectively. Results verified that the constraints of conventional anaerobic digestion for food waste or sewage sludge separately could be overcome by synergistic effect of co-digestion strategy and two-phase treatment.

Effect of Hydraulic Retention Time on Pretreatment of Sulfate-Laden Wastewater for Desulfurization-Denitrification Process

2010 ◽  
Vol 113-116 ◽  
pp. 536-539
Author(s):  
Wei Li ◽  
Xiao Liang ◽  
Jian Guo Lin
Keyword(s):  
Organic Carbon ◽  
Sulfate Reduction ◽  
Retention Time ◽  
Hydraulic Retention Time ◽  
Removal Rate ◽  
Reduction Stage ◽  
Sulfate Removal ◽  
Carbon Sulfide ◽  
Set Up ◽  
Denitrification Process

In order to treat wastewater rich in sulfate and organic carbon, an anaerobic attached-growth bioreactor was set up. It was the pretreatment of desulfurization-denitrification process. At hydraulic retention time of 128h-6.2h, sulfate removal rate and sulfide generating rate took on initial increasing and subsequent decreasing. At hydraulic retention time of 7.7h-10.2h, the removals of sulfate and organic carbon, sulfide generating rate reached 95.79%, 80% and 58.82%, respectively. The results showed that the suitable hydraulic retention time in sulfate reduction stage for the pretreatment of desulfurization-denitrification process was 7.7h-10.2h.

scholarly journals Nitrifying and heterotrophic population dynamics in biofilm reactors: effects of hydraulic retention time and the presence of organic carbon

2002 ◽  
Vol 36 (2) ◽  
pp. 469-481 ◽  
Author(s):  
Regina Nogueira ◽  
Luı́s F Melo ◽  
Ulrike Purkhold ◽  
Stefan Wuertz ◽  
Michael Wagner
Keyword(s):  
Population Dynamics ◽  
Organic Carbon ◽  
Retention Time ◽  
Hydraulic Retention Time ◽  
Biofilm Reactors

scholarly journals Impact of hydraulic retention time on phosphorus removal from wastewater using reactive media

2020 ◽  
Vol 82 (12) ◽  
pp. 2920-2928
Author(s):  
S. Benzing ◽  
F. Couceiro ◽  
S. Barnett ◽  
J. B. Williams ◽  
P. Pearce ◽  
...  
Keyword(s):  
Retention Time ◽  
Hydraulic Retention Time ◽  
Wastewater Treatment Plants ◽  
Appropriate Technology ◽  
Synthetic Wastewater ◽  
Depth Analysis ◽  
The Impact ◽  
Over Time ◽  
P Removal ◽  
Reactive Media

Abstract Phosphorus (P) discharge from wastewater treatment plants into the environment contributes to eutrophication issues. Reactive media filters represent an effective, simple and cost-effective solution to decrease the P content. Previous research used various experimental designs and often synthetic wastewater, making assessment of real-world performance difficult. This study assesses the impact of the hydraulic retention time (HRT) on P removal using real wastewater to refine design criteria for full-scale installations. Four media were compared in column experiments for >200 days. Different HRTs were applied and initially the media achieved low P effluent concentrations of >0.1 mg/L PO4–P, increasing over time. Best P removal was observed for the highest HRT with on average >99%. HRT was seen to be the driving factor for P removal rather than media capacity. Three of the four materials showed pH levels above 12 initially, decreasing over time. Water quality parameters, including organics, solids and metals, were monitored. In-depth analysis confirmed formation of calcium phosphate precipitation on the media's surface. The results suggest the importance of an optimal HRT to achieve high P removal and show that the reactive media application is an appropriate technology for P removal on small sites if the elevated pH is addressed.

Ozonation of nursing home wastewater pretreated in a membrane bioreactor

2018 ◽  
Vol 78 (2) ◽  
pp. 266-278 ◽  
Author(s):  
Danièle Mousel ◽  
Johannes Pinnekamp
Keyword(s):  
Nursing Home ◽  
Organic Carbon ◽  
Retention Time ◽  
Membrane Bioreactor ◽  
Municipal Wastewater ◽  
Hydraulic Retention Time ◽  
Plant Size ◽  
Treated Wastewater ◽  
Pharmaceutically Active Compounds ◽  
Recommended Dosage

Abstract Nursing home (NH) wastewater was pretreated in an ultrafiltration membrane bioreactor (MBR) and subsequently ozonated in a pilot plant in order to evaluate the elimination of pharmaceutically active compounds (PhACs). Dosing of the pre-treated wastewater with 5 mg ozone (O3) L−1 led to the elimination of >50% for nearly all investigated PhACs in the ozonation plant, whereas dosing 10 mg O3 L−1 increased elimination to >80%. A total hydraulic retention time of 12.8 min proved sufficient for PhAC elimination. Specific ozone consumption and influent dissolved organic carbon (DOC) (8.2–9.5 mg L−1) were in similar ranges for all three performed trials. Combining the MBR with subsequent ozonation at a dosage of 5 mg O3 L−1 achieved elimination of >90% and effluent concentrations below 250 ng L−1 for nearly all the investigated PhACs. Influent concentrations of the MBR were comparable to those found in municipal wastewater. Thus, the recommended dosage for PhAC elimination of 5 mg O3 L−1 (i.e. a specific consumption of 0.6 g O3*(g DOC)−1) is in the same range as for municipal wastewater. However, due to a smaller plant size, the specific costs for treating NH wastewater would significantly exceed those of treating municipal wastewater.

scholarly journals Strategies to Optimize Microalgae Conversion to Biogas: Co-Digestion, Pretreatment and Hydraulic Retention Time

Molecules ◽  
2018 ◽  
Vol 23 (9) ◽  
pp. 2096 ◽  
Author(s):  
Maria Solé-Bundó ◽  
Humbert Salvadó ◽  
Fabiana Passos ◽  
Marianna Garfí ◽  
Ivet Ferrer
Keyword(s):  
Retention Time ◽  
Cell Walls ◽  
Hydraulic Retention Time ◽  
Microscopic Analysis ◽  
Fold Increase ◽  
Resistant Cell ◽  
Methane Yield ◽  
Thermal Pretreatment ◽  
Primary Sludge ◽  
Yield Increase

This study aims at optimizing the anaerobic digestion (AD) of biomass in microalgal-based wastewater treatment systems. It comprises the co-digestion of microalgae with primary sludge, the thermal pretreatment (75 °C for 10 h) of microalgae and the role of the hydraulic retention time (HRT) in anaerobic digesters. Initially, a batch test comparing different microalgae (untreated and pretreated) and primary sludge proportions showed how the co-digestion improved the AD kinetics. The highest methane yield was observed by adding 75% of primary sludge to pretreated microalgae (339 mL CH4/g VS). This condition was then investigated in mesophilic lab-scale reactors. The average methane yield was 0.46 L CH4/g VS, which represented a 2.9-fold increase compared to pretreated microalgae mono-digestion. Conversely, microalgae showed a low methane yield despite the thermal pretreatment (0.16 L CH4/g VS). Indeed, microscopic analysis confirmed the presence of microalgae species with resistant cell walls (i.e., Stigioclonium sp. and diatoms). In order to improve their anaerobic biodegradability, the HRT was increased from 20 to 30 days, which led to a 50% methane yield increase. Overall, microalgae AD was substantially improved by the co-digestion with primary sludge, even without pretreatment, and increasing the HRT enhanced the AD of microalgae with resistant cell walls.

Reducing hydraulic short-circuiting in maturation ponds to maximize pathogen removal using channels and wind breaks

2003 ◽  
Vol 48 (2) ◽  
pp. 153-162 ◽  
Author(s):  
B.J. Lloyd ◽  
C.A. Vorkas ◽  
R.K. Guganesharajah
Keyword(s):  
Retention Time ◽  
Hydraulic Retention Time ◽  
Plug Flow ◽  
Surface Flow ◽  
Faecal Coliform ◽  
Coliform Bacteria ◽  
Faecal Coliforms ◽  
Log Reduction ◽  
Time Flow ◽  
The Impact

This paper reports the impact of four sequential maturation pond interventions on the removal of thermotolerant “faecal” coliform bacteria at a full scale WSP system in tropical Colombia. Each intervention was designed to increase hydraulic retention time and was followed by continuous physico-chemical logging and meteorological monitoring, and simultaneous tracer studies to define hydraulic retention time, flow paths and dispersion. Inlet and outlet monitoring showed that, primarily due to hydraulic short-circuiting, the open maturation pond only achieved a 90% reduction in thermotolerant “faecal” coliforms. By contrast, an in-pond batch decay rate study for thermotolerant faecal coliforms showed that a 1 log (90%) reduction was achieved every 24 hours for 4 days at 26°C, so that the maximum theoretical efficiency would be a 2.6 log reduction (99.7%) if hydraulic efficiency was perfect for plug flow. The second intervention was the conversion of the maturation pond to a parallel series of three open channels to attempt to control short-circuiting and convert to plug flow. The channels raised performance to 96%. The introduction of top baffles, at the end of the first and second channels, to attempt to further reduce the effect of surface and sub-surface flow on short-circuiting, actually reduced performance to 92.64%, and were removed. The final intervention, a 2.1 m high wind break around the maturation channels raised efficiency to 98.13%; this performance is almost a half log (0.47) greater than the efficiency (95.1%) predicted from Marais' equation for a completely mixed reactor, and 0.77 log greater than recorded in the open pond. The results have fundamental implications for improving WSP efficiency, for meeting re-use guidelines, for savings in land area and improvement of design of WSPs; they also highlight short-comings in the indiscriminate use of the Marais design equation for faecal coliform removal.

scholarly journals Performance of Aerobic Microbial Granules in Organic Carbon Removal as a Method in the Treatment of Biodegradable Wastewater

2019 ◽  
Vol 125 ◽  
pp. 03014
Author(s):  
Nanik Indah Setianingsih ◽  
Hadiyanto ◽  
Sudarno ◽  
Rustiana Yuliasni
Keyword(s):  
Wastewater Treatment ◽  
Organic Carbon ◽  
Retention Time ◽  
Biological Treatment ◽  
High Performance ◽  
Settling Velocity ◽  
Hydraulic Retention Time ◽  
Excess Sludge ◽  
Large Area ◽  
Anaerobic System

Conventional biological wastewater treatment is effective in removing organic carbon but has weaknesses in need large area, long hydraulic retention time, produce excess sludge in activated sludge system and need post treatment for removing nutrient in the anaerobic system. Aerobic microbial granules is a biological method in wastewater treatment that potential to overcome the lack of conventional biological treatment. Aerobic granules were developed in SBR made of glass with an effective volume of 10 L. Acetate was used as a source of carbon with COD concentration 900-1200 mg/L. SBR was run in anaerobic and aerobic phase with a hydraulic retention time of 8,3 hours and an exchange ratio of 60%. Granules begin to be formed after 14 days operational period with SVI30 to SVI5 ratio reach on 0,97 and settling velocity 13,8 cm/minute. High performance in degrading organic carbon is shown by aerobic microbial granules system with removal efficiency reaches on 94-97%.

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