Treatment of Agricultural Wastewater in a Combined Tidal Flow-downflow Reed Bed System

1999 ◽  
Vol 40 (3) ◽  
pp. 139-146 ◽  
Author(s):  
G. Sun ◽  
K. R. Gray ◽  
A. J. Biddlestone ◽  
D. J. Cooper
Keyword(s):  
Water Movement ◽  
Tidal Flow ◽  
Treated Wastewater ◽  
Mean Flow ◽  
Combined System ◽  
Agricultural Wastewater ◽  
The Matrix ◽  
Water Recirculation ◽  
Reed Bed ◽  
Suitable Technique

In this study, the efficacy of a full-scale combined tidal flow-downflow reed bed system was tested for the treatment of agricultural wastewater with average BOD5 of 1100 mg/l and NH4-N of 329.5 mg/l. At a mean flow rate of 2.0 m3/d, the BOD5 and COD of the influent were reduced across the system by 97.6% and 71.3%, respectively. Considerable SS and PO4-P removals were also achieved. NH4-N was reduced by 93.1%. Nitrification proved to be the major process for NH4-N reduction. Although a further polishing treatment is needed, the average BOD5 and NH4-N levels of the treated wastewater were close to those frequently required in UK discharge consents. The highest BOD5, COD and NH4-N removals and oxygen consumption rate were achieved in the tidal flow stage of the combined system; this suggests that the rhythmical air/water movement in the matrix of the tidal flow beds can benefit the treatment by providing higher oxygen flux and more efficient utilisation of the available bed volume. Better results for BOD5, COD and NH4-N removals were obtained in downflow beds with water recirculation than in those without this recycle. Therefore the recirculation of effluent around each treatment stage is a suitable technique for improving the performance of downflow reed beds.

scholarly journals Optimising the performance of a lab-scale tidal flow reed bed system treating agricultural wastewater

2004 ◽  
Vol 50 (8) ◽  
pp. 65-72 ◽  
Author(s):  
Y.Q. Zhao ◽  
G. Sun ◽  
C. Lafferty ◽  
S.J. Allen
Keyword(s):  
Tidal Flow ◽  
High Strength ◽  
Pollutant Removal ◽  
Inorganic Pollutants ◽  
Operational Conditions ◽  
Agricultural Wastewater ◽  
Major Route ◽  
Reed Bed ◽  
Ammoniacal Nitrogen Removal

A gravel-based tidal flow reed bed system was operated with three different strategies in order to investigate its optimal performance for the treatment of a high strength agricultural wastewater. According to the three strategies, individual reed beds were saturated and unsaturated with the wastewater for different periods while reasonably stable hydraulic and organic loadings were maintained. Experimental results demonstrated that the system produced the highest pollutant removal efficiencies with a relatively short saturated period and long unsaturated period, highlighting the importance of oxygen transfer into reed bed matrices during the treatment. Significant removals of some major organic and inorganic pollutants were achieved under all three operational conditions. Nitrification was not the major route of ammoniacal-nitrogen removal when the system was under high organic loading. Due to the filtration of suspended solids and the accumulation of biomass, gradual clogging of the reed bed matrices took place, which caused concerns over the long-term efficiency of the tidal flow system.

Treatment of Agricultural Wastewater in a Pilot-Scale Tidal Flow Reed Bed System

1999 ◽  
Vol 20 (2) ◽  
pp. 233-237 ◽  
Author(s):  
G. Sun ◽  
K. R. Gray ◽  
A. J. Biddlestone
Keyword(s):  
Tidal Flow ◽  
Pilot Scale ◽  
Agricultural Wastewater ◽  
Reed Bed

Helminth eggs in wastewater: quantification technique

1995 ◽  
Vol 31 (5-6) ◽  
pp. 443-446 ◽  
Author(s):  
P. G. Gaspard ◽  
J. Schwartzbrod
Keyword(s):  
Waste Water ◽  
Water Analysis ◽  
Zinc Sulphate ◽  
Wastewater Reuse ◽  
Treated Wastewater ◽  
Agricultural Wastewater ◽  
Helminth Eggs ◽  
Waste Water Analysis ◽  
Good Homogeneity

In the framework of agricultural wastewater reuse, the W.H.O. has defined a parasitological quality for sewage with less than one nematode egg per liter. The purpose of this work is to define an effective method to detect helminth eggs in wastewater. Seven techniques have been applied to waste water analysis, with a comparison of their respective results, varying from 26 to 74 %. Be it in the framework of artificial contamination or on site, the best results were obtained with the diphasic technique perfected at the laboratory including a treatment with antiformine at 8 % + ethylacetate followed by a flotation with zinc sulphate at 55%. The validation in the laboratory of the methods performance on treated wastewater allowed us to show that the yield of the method is significantly independent of the egg concentration as well as giving good homogeneity of results with a concentration of 1 egg/litre.

scholarly journals Assessment of alternative land management practices using hydrological simulation and a decision support tool: Arborea agricultural region, Sardinia

2007 ◽  
Vol 11 (6) ◽  
pp. 1811-1823 ◽  
Author(s):  
P. Cau ◽  
C. Paniconi
Keyword(s):  
Decision Support ◽  
Land Management ◽  
Quantitative Methods ◽  
Management Practices ◽  
Water Movement ◽  
Agricultural Practices ◽  
Treated Wastewater ◽  
Hydrological Simulation ◽  
Support Tool ◽  
The Impact

Abstract. Quantifying the impact of land use on water supply and quality is a primary focus of environmental management. In this work we apply a semidistributed hydrological model (SWAT) to predict the impact of different land management practices on water and agricultural chemical yield over a long period of time for a study site situated in the Arborea region of central Sardinia, Italy. The physical processes associated with water movement, crop growth, and nutrient cycling are directly modeled by SWAT. The model simulations are used to identify indicators that reflect critical processes related to the integrity and sustainability of the ecosystem. Specifically we focus on stream quality and quantity indicators associated with anthropogenic and natural sources of pollution. A multicriteria decision support system is then used to develop the analysis matrix where water quality and quantity indicators for the rivers, lagoons, and soil are combined with socio-economic variables. The DSS is used to assess four options involving alternative watersheds designated for intensive agriculture and dairy farming and the use or not of treated wastewater for irrigation. Our analysis suggests that of the four options, the most widely acceptable consists in the transfer of intensive agricultural practices to the larger watershed, which is less vulnerable, in tandem with wastewater reuse, which rates highly due to water scarcity in this region of the Mediterranean. More generally, the work demonstrates how both qualitative and quantitative methods and information can assist decision making in complex settings.

E. coli transport in soil columns: implications for reuse of treated wastewater in irrigation

2006 ◽  
Vol 54 (11-12) ◽  
pp. 175-182 ◽  
Author(s):  
E. Smith ◽  
S. Hegazy
Keyword(s):  
Groundwater Resources ◽  
Soil Column ◽  
Management Plan ◽  
Treated Wastewater ◽  
Soil Columns ◽  
E Coli ◽  
The Matrix ◽  
The Impact ◽  
Reuse Of Treated Wastewater ◽  
Vital Element

Reuse of treated wastewater in irrigation is gaining recognition as a vital element in the water resources management plan of developing countries, especially those situated in arid and semi-arid regions. An understanding of the transport of residual pollutants from treated wastewater, such as bacteria, in soil as a result of irrigation is critical to assessing health risks and the possible contamination of limited groundwater resources. In this work, retention of E. coli is evaluated for a soil that is irrigated by treated wastewater for growth of non-food crops near Egypt's Red Sea coast. In particular, the effects of soil organic fraction (SOF) and hydraulic loading rate (HLR) were investigated in laboratory soil columns. The matrix of experiments included three HLRs and three SOFs. The retention of bacteria by adsorption was observed at HLRs of 5 and 13 cm/h, with the magnitude of the adsorption increasing proportionally to the SOF. The impact of SOF was greater for the lower HLR. At the lowest HLR investigated (5 cm/h), filtration was also observed for the two higher SOFs (0.674 and 2.04 per cent). At a high HLR (66 cm/h) simulating flood irrigation, retention of bacteria was minimal regardless of the SOF. Since the bacterial solution is applied to a dry soil column to simulate field conditions, E. coli breakthrough after two pore volumes of throughput (vs. one) provided a meaningful comparison of bacterial retention as a function of HLR and SOF.

Effect of effluent recirculation on the performance of a reed bed system treating agricultural wastewater

2003 ◽  
Vol 39 (3) ◽  
pp. 351-357 ◽  
Author(s):  
G. Sun ◽  
K.R. Gray ◽  
A.J. Biddlestone ◽  
S.J. Allen ◽  
D.J. Cooper
Keyword(s):  
Agricultural Wastewater ◽  
Effluent Recirculation ◽  
Reed Bed

scholarly journals Turbulence closure: turbulence, waves and the wave-turbulence transition – Part 1: Vanishing mean shear

2008 ◽  
Vol 5 (4) ◽  
pp. 545-580
Author(s):  
H. Z. Baumert ◽  
H. Peters
Keyword(s):  
Internal Wave ◽  
Internal Waves ◽  
Tidal Flow ◽  
Wave Turbulence ◽  
Mean Flow ◽  
Turbulent Length Scale ◽  
Turbulent Dissipation ◽  
New Model ◽  
Turbulence Transition ◽  
Ozmidov Scale

Abstract. A new two-equation, closure-like turbulence model for stably stratified flows is introduced which uses the turbulent kinetic energy (K) and the turbulent enstrophy (Ω) as primary variables. It accounts for mean shear – and internal wave-driven mixing in the two limits of mean shear and no waves and waves but no mean shear, respectively. The traditional TKE balance is augmented by an explicit energy transfer from internal waves to turbulence. A modification of the Ω-equation accounts for the effect of the waves on the turbulence time and space scales. The latter is based on the assumption of a non-zero constant flux Richardson number in the limit of vanishing mean-flow shear when turbulence is produced exclusively by internal waves. The new model reproduces the wave-turbulence transition analyzed by D'Asaro and Lien (2000). At small energy density E of the internal wave field, the turbulent dissipation rate (ε) scales like ε~E2. This is what is observed in the deep sea. With increasing E, after the wave-turbulence transition has been passed, the scaling changes to ε~E1. This is observed, for example, in the swift tidal flow near a sill in Knight Inlet. The new model further exhibits a turbulent length scale proportional to the Ozmidov scale, as observed in the ocean, and predicts the ratio between the turbulent Thorpe and Ozmidov length scales well within the range observed in the ocean.

scholarly journals Experiences of running a hydroponic system in a pilot scale for resource-efficient water reuse

2020 ◽  
Vol 10 (4) ◽  
pp. 347-362 ◽  
Author(s):  
Alexa Bliedung ◽  
Thomas Dockhorn ◽  
Jörn Germer ◽  
Claudia Mayerl ◽  
Marius Mohr
Keyword(s):  
Plant Growth ◽  
Pilot Plant ◽  
Water Reuse ◽  
Pilot Scale ◽  
Plant Production ◽  
Treated Wastewater ◽  
Nutrient Concentrations ◽  
Combined System ◽  
Modes Of Operation ◽  
Hydroponic System

Abstract Within the research project HypoWave, a hydroponic system for plant production was investigated. The hydroponic system was fed with wastewater that had undergone specially adapted treatment. The principal aim was to develop a combined system for water treatment and hydroponic plant production, where water and nutrients were reused efficiently to produce marketable food products. Another goal was to find out whether the reuse of pre-treated wastewater for plant growth in a hydroponic system could also present an additional alternative wastewater treatment step for enhanced nutrient removal. A pilot plant, consisting of various treatment steps such as activated sludge process, ozonation and biological activated carbon filtration, was used to produce lettuce with irrigation water of different qualities. The hydroponic pilot plant was operated in two different modes – flow-through and feed & deplete. This paper focuses on the influence of the various modes of operation and accordingly varying nutrient concentrations (N, P, K) on plant growth. Furthermore, heavy metal content in the various types of treated wastewater and in the produced plants was investigated. In addition, the results of the different modes of operation were verified by mass balances for N, P and K.

Sign in / Sign up

Export Citation Format

Share Document