Onsite wastewater nitrogen reduction with expanded media and elemental sulfur biofiltration

2012 ◽  
Vol 65 (4) ◽  
pp. 750-756 ◽  
Author(s):  
D. P. Smith
Keyword(s):  
Elemental Sulfur ◽  
Organic N ◽  
Small Scale ◽  
Vertical Flow ◽  
High Nitrogen ◽  
Unsaturated Media ◽  
Onsite Wastewater ◽  
Reduction Efficiency ◽  
In Series ◽  
Inlet Zone

A passive biofiltration process has been developed to enhance nitrogen removal from onsite sanitation water. The system employs an initial unsaturated vertical flow biofilter with expanded clay media (nitrification), followed in series by a horizontal saturated biofilter for denitrification containing elemental sulfur media as electron donor. A small-scale prototype was operated continuously over eight months on primary wastewater effluent with total nitrogen (TN) of 72.2 mg/L. The average hydraulic loading to the unsaturated biofilter surface was 11.9 cm/day, applied at a 30 min dosing cycle. Average effluent TN was 2.6 mg/L and average TN reduction efficiency was 96.2%. Effluent nitrogen was 1.7 mg/L as organic N, 0.93 mg/L as ammonium (NH4-N), and 0.03 as oxidized (NO3 + NO2) N. There was no surface clogging of unsaturated media, nitrate breakthrough, or replenishment of sulfur media over eight months. Visual and microscopic examinations revealed substantially open pores with limited material accumulation on the upper surface of the unsaturated media. Material accumulation was observed at the inlet zone of the denitrification biofilter, and sulfur media exhibited surface cavities consistent with oxidative dissolution. Two-stage biofiltration is a simple and resilient system for achieving high nitrogen reductions in onsite wastewater.

scholarly journals Treatment performances of French constructed wetlands: results from a database collected over the last 30 years

2015 ◽  
Vol 71 (9) ◽  
pp. 1333-1339 ◽  
Author(s):  
A. Morvannou ◽  
N. Forquet ◽  
S. Michel ◽  
S. Troesch ◽  
P. Molle
Keyword(s):  
Constructed Wetlands ◽  
Oxygen Demand ◽  
Pollutant Removal ◽  
Vertical Flow ◽  
Removal Rates ◽  
Waste Stabilization Ponds ◽  
Small Communities ◽  
Technical Department ◽  
In Series ◽  
High Chemical Oxygen Demand

Approximately 3,500 constructed wetlands (CWs) provide raw wastewater treatment in France for small communities (<5,000 people equivalent). Built during the past 30 years, most consist of two vertical flow constructed wetlands (VFCWs) in series (stages). Many configurations exist, with systems associated with horizontal flow filters or waste stabilization ponds, vertical flow with recirculation, partially saturated systems, etc. A database analyzed 10 years earlier on the classical French system summarized the global performances data. This paper provides a similar analysis of performance data from 415 full-scale two-stage VFCWs from an improved database expanded by monitoring data available from Irstea and the French technical department. Trends presented in the first study are confirmed, exhibiting high chemical oxygen demand (COD), total suspended solids (TSS) and total Kjeldahl nitrogen (TKN) removal rates (87%, 93% and 84%, respectively). Typical concentrations at the second-stage outlet are 74 mgCOD L−1, 17 mgTSS L−1 and 11 mgTKN L−1. Pollutant removal performances are summarized in relation to the loads applied at the first treatment stage. While COD and TSS removal rates remain stable over the range of applied loads, the spreading of TKN removal rates increases as applied loads increase.

Nitrogen Transformations and Removal in Waste Stabilization Ponds in Portugal: Seasonal Variations

1987 ◽  
Vol 19 (12) ◽  
pp. 123-130 ◽  
Author(s):  
M. C. R. Santos ◽  
J. F. S. Oliveira
Keyword(s):  
Seasonal Variations ◽  
Climatic Factors ◽  
Weather Conditions ◽  
Organic N ◽  
Nitrogen Transformations ◽  
Waste Stabilization Ponds ◽  
N Transformations ◽  
Temperature And Precipitation ◽  
N Removal ◽  
In Series

Nitrogen transformations that can occur in WSP depend on pond and waste characteristics and are also influenced by climatic factors, like temperature and precipitation. Experiments described have been carried out using a system of three ponds in series: anaerobic, facultative and maturation, treating domestic sewage. In this paper we aim to identify the processes that might contribute to N transformations in each pond and the seasonal variations in the removal of nitrogen and its bioconversion throughout the year. Results have proved that there was an important organic N removal in the anaerobic pond, mainly due to mineralisation and not exclusively by sedimentation. Some of the processes of N transformation observed in the ponds were more strongly influenced by weather conditions than others. In some cases, the increase of biological activity that was induced by the increase in air temperature, was masked by reduced precipitation which produced less diluted treated effluents. These climatic factors can explain some of the variations observed along the year, in what concerns nitrogen compounds concentrations.

Pig Wastewater Treatment in Water Hyacinth Ponds

1992 ◽  
Vol 26 (9-11) ◽  
pp. 2381-2384 ◽  
Author(s):  
C. Polprasert ◽  
S. Kessomboon ◽  
W. Kanjanaprapin
Keyword(s):  
Wastewater Treatment ◽  
Water Hyacinth ◽  
Loading Rate ◽  
Pilot Scale ◽  
Operating Conditions ◽  
Cod Removal ◽  
Organic Loading Rate ◽  
Small Scale ◽  
N Removal ◽  
In Series

Small-scale and pilot-scale experiments were conducted on pig wastewater treatment in water hyacinth (Eichhornia crassipesl ponds. The main objectives were to evaluate the treatment performance of the water hyacinth ponds and to determine suitable operating conditions. From the experimental results obtained, the optimum organic loading rate was found to be 200 kg COD/(ha.d), while the hydraulic retention times were proposed to be 10-20 days. The % COD removal in the small-scale water hyacinth ponds were 74-93, while for the pilot-scale ponds the % COD removal were 52-72 because of fluctuations in the influent wastewater characteristics and occasional insect attacks on the water hyacinth leaves and stems. Similar results were obtained for N removal. Although the water hyacinth ponds were found to be feasible for pig wastewater treatment, at least one polishing pond in series should be provided to polish the water hyacinth pond effluents before discharging into the environment.

Evaluation of nitrate and perchlorate reduction using sulfur-based autotrophic and mixotrophic denitrifying processes

2015 ◽  
Vol 16 (1) ◽  
pp. 208-218 ◽  
Author(s):  
Deniz Uçar ◽  
Emine Ubay Çokgör ◽  
Erkan Şahinkaya
Keyword(s):  
Nitrate Reduction ◽  
Elemental Sulfur ◽  
Reduction Rate ◽  
Sulfate Concentration ◽  
Biological Reduction ◽  
Perchlorate Reduction ◽  
Guideline Value ◽  
Reduction Efficiency ◽  
Drinking Water Guideline ◽  
Denitrification Process

The biological reduction of nitrate and perchlorate was comparatively evaluated in autotrophic and mixotrophic bioreactors using elemental sulfur and/or methanol as the energy source. The mixotrophic reactor was supplemented with methanol at CH3OH/NO3−-N ratio of 1 or 1.4. The mixotrophic reactor completely reduced perchlorate in the feed up to 1,000 μg l−1. The autotrophic reactor also showed high perchlorate reduction performance and decreased perchlorate from 1,000 μg l−1 to around 33 μg l−1. Complete reduction of 25 mg NO3−-N l−1 was achieved in both reactors, corresponding to a maximum nitrate reduction rate of 300 mg NO3−-N l−1d−1 and 400 mg NO3−-N l−1d−1 in the autotrophic and mixotrophic processes, respectively. Autotrophic denitrification caused an increase of effluent sulfate concentration, which may exceed the drinking water guideline value of 250 mg l−1. In the mixotrophic denitrification process, the effluent sulfate concentration was controlled by adjusting the C/N ratio in the influent. Mixotrophic denitrification was stimulated by 25 mg l−1 methanol addition and 53% of influent nitrate was reduced by the heterotrophic process, which decreased the effluent sulfate concentration to half of the autotrophic counterpart. Therefore, the mixotrophic process may be preferred over the autotrophic process when effluent sulfate concentration is of concern and a higher perchlorate reduction efficiency is desired.

Dynamics of a Large Scale Hydraulic Capsule Pipeline System

1999 ◽  
Vol 124 (1) ◽  
pp. 191-195 ◽  
Author(s):  
Hongliu Du ◽  
Satish S. Nair
Keyword(s):  
Large Scale ◽  
Control Method ◽  
Experimental Studies ◽  
Small Scale ◽  
Pipeline System ◽  
Centrifugal Pumps ◽  
Long Distance ◽  
Column Separation ◽  
In Series ◽  
Hydraulic Capsule Pipeline

The dynamics of a booster station, which is critical for the control of a novel, long distance, hydraulic capsule pipeline, is simulated mathematically for design studies and control of the hydraulic transients caused by the valve actuators in the system. Several modifications to the pump bypass station configuration of the booster station have been studied. With the objective of eliminating column separation and reducing flow reversals, a configuration with several centrifugal pumps connected in series, and a carefully sized air chamber is found to be a viable design. A valve control method is designed to eliminate column separation and the design results in acceptable flow reversal levels in the main pipe. The simulation results match with trends in limited experimental studies performed on a small scale experimental capsule pipeline system.

Small-scale statistics in high-resolution direct numerical simulation of turbulence: Reynolds number dependence of one-point velocity gradient statistics

2007 ◽  
Vol 592 ◽  
pp. 335-366 ◽  
Author(s):  
T. ISHIHARA ◽  
Y. KANEDA ◽  
M. YOKOKAWA ◽  
K. ITAKURA ◽  
A. UNO
Keyword(s):  
Reynolds Number ◽  
High Resolution ◽  
Longitudinal Velocity ◽  
Second Order ◽  
Distribution Functions ◽  
Small Scale ◽  
Kolmogorov Length Scale ◽  
Velocity Gradients ◽  
In Series ◽  
Derivatives Of

One-point statistics of velocity gradients and Eulerian and Lagrangian accelerations are studied by analysing the data from high-resolution direct numerical simulations (DNS) of turbulence in a periodic box, with up to 40963 grid points. The DNS consist of two series of runs; one is with kmaxη ~ 1 (Series 1) and the other is with kmaxη ~ 2 (Series 2), where kmax is the maximum wavenumber and η the Kolmogorov length scale. The maximum Taylor-microscale Reynolds number Rλ in Series 1 is about 1130, and it is about 675 in Series 2. Particular attention is paid to the possible Reynolds number (Re) dependence of the statistics. The visualization of the intense vorticity regions shows that the turbulence field at high Re consists of clusters of small intense vorticity regions, and their structure is to be distinguished from those of small eddies. The possible dependence on Re of the probability distribution functions of velocity gradients is analysed through the dependence on Rλ of the skewness and flatness factors (S and F). The DNS data suggest that the Rλ dependence of S and F of the longitudinal velocity gradients fit well with a simple power law: S ~ −0.32Rλ0.11 and F ~ 1.14Rλ0.34, in fairly good agreement with previous experimental data. They also suggest that all the fourth-order moments of velocity gradients scale with Rλ similarly to each other at Rλ > 100, in contrast to Rλ < 100. Regarding the statistics of time derivatives, the second-order time derivatives of turbulent velocities are more intermittent than the first-order ones for both the Eulerian and Lagrangian velocities, and the Lagrangian time derivatives of turbulent velocities are more intermittent than the Eulerian time derivatives, as would be expected. The flatness factor of the Lagrangian acceleration is as large as 90 at Rλ ≈ 430. The flatness factors of the Eulerian and Lagrangian accelerations increase with Rλ approximately proportional to RλαE and RλαL, respectively, where αE ≈ 0.5 and αL ≈ 1.0, while those of the second-order time derivatives of the Eulerian and Lagrangian velocities increases approximately proportional to RλβE and RλβL, respectively, where βE ≈ 1.5 and βL ≈ 3.0.

scholarly journals Irrigation return flow causing a nitrate hotspot and denitrification imprints in groundwater at Tinwald, New Zealand

2020 ◽  
Vol 24 (7) ◽  
pp. 3583-3601
Author(s):  
Michael Kilgour Stewart ◽  
Philippa Lauren Aitchison-Earl
Keyword(s):  
Stable Isotopes ◽  
Local Community ◽  
Economic Cost ◽  
Flow Coefficient ◽  
Organic N ◽  
Nitrate Transport ◽  
Small Scale ◽  
Return Flow ◽  
Irrigation Flow ◽  
Irrigation Return Flow

Abstract. Nitrate concentrations in groundwater have been historically high (N≥11.3 mg L−1) in an area surrounding Tinwald, Ashburton, since at least the mid-1980s. The local community is interested in methods to remediate the high nitrate in groundwater. To do this, they need to know where the nitrate is coming from. Tinwald groundwater exhibits two features stemming from irrigation with local groundwater (i.e. irrigation return flow). The first feature is increased concentrations of nitrate (and other chemicals and stable isotopes) in a “hotspot” around Tinwald. The chemical concentrations of the groundwater are increased by recirculation of water already relatively high in chemicals. The irrigation return flow coefficient C (irrigation return flow divided by irrigation flow) is found to be consistent with the chemical enrichments. The stable isotopes of the groundwater show a similar pattern of enrichment by irrigation return flow of up to 40 % and are also enriched by evaporation (causing a loss of about 5 % of the original water mass). Management implications are that irrigation return flow needs to be taken into account in modelling of nitrate transport through soil–groundwater systems and in avoiding overuse of nitrate fertiliser leading to greater leaching of nitrate to the groundwater and unnecessary economic cost. The second feature is the presence of “denitrification imprints” (shown by enrichment of the δ15N and δ18ONO3 values of nitrate) in even relatively oxic groundwaters. The denitrification imprints can be clearly seen because (apart from denitrification) the nitrate has a blended isotopic composition due to irrigation return flow and N being retained in the soil–plant system as organic N. The nitrate concentration and isotopic compositions of nitrate are found to be correlated with the dissolved oxygen (DO) concentration. This denitrification imprint is attributed to localised denitrification in fine pores or small-scale physical heterogeneity where conditions are reducing. The implication is that denitrification could be occurring where it is not expected because groundwater DO concentrations are not low.

scholarly journals The Development of a Decision Support Software for the Design of Micro-Hydropower Schemes Utilizing a Pump as Turbine

Proceedings ◽  
2018 ◽  
Vol 2 (11) ◽  
pp. 678 ◽  
Author(s):  
Daniele Novara ◽  
Aonghus McNabola
Keyword(s):  
Energy Recovery ◽  
Small Scale ◽  
Reverse Mode ◽  
Trade Offs ◽  
Visual Aid ◽  
In Series ◽  
Support Software ◽  
Water Pumps

Pumps As Turbines (PATs) are a class of unconventional hydraulic turbines consisting of standard water pumps working in reverse mode as the prime mover. Such devices can be well suited for either in-pipe energy recovery or small-scale hydropower, but their practical application is hampered by the lack of comprehensive guidelines able to assist the designer in the determination of the optimal plant layout and the choice of equipment. In fact, the performances of a PAT will depend on factors such as its construction type, its size and the flow conditions under which the machine is expected to operate. Ultimately, the design of a PAT-based hydro scheme is a matter of trade-offs which are in most cases not trivial. An innovative software was developed in order to assist hydro designers and provide a visual aid when choosing between different layouts of the analyzed hydro scheme (e.g., more than one PAT in series/parallel, different shaft speeds), and has been applied to a real case study of energy recovery in a water network.

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