The advantages of a constructed reed bed based strategy for small sewage treatment works

The advantages of the use by a major UK water utility serving 8 million people in central England of constructed subsurface flow reed beds for secondary, tertiary and storm water treatment at small sewage treatment works is placed in context with improved permit compliance to more stringent standards and a continuing downward pressure on operating costs. Capital and energy costs are compared with the competing tertiary treatment process of recirculating sand filtration. Further economic advantage is gained by combining tertiary treatment and stormwater treatment. With over 160 sites in operation by mid 1997 the success of the strategy has given confidence to allow for the early or emergency installation of reed beds to improve or maintain effluent quality before replacement, or in one case the provision, of secondary treatment. Use of constructed reed beds is now being extended to larger facilities where only a proportion of the flow needs to be treated to achieve standards. For tertiary treatment reed beds there is an additional environmental benefit with the typical removal of 10.7 mg/l of total nitrogen.

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Ten years experience of treating all flows from combined sewerage systems using package plant and constructed wetland combinations

Water Science & Technology ◽

10.2166/wst.2004.0813 ◽

2004 ◽

Vol 48 (11-12) ◽

pp. 93-99 ◽

Cited By ~ 6

Author(s):

P. Griffin

Keyword(s):

Constructed Wetlands ◽

Constructed Wetland ◽

Stormwater Treatment ◽

Tertiary Treatment ◽

Reed Beds ◽

Effluent Quality ◽

Rotating Biological Contactors ◽

Dry Weather Flow

Severn Trent Water have been using constructed wetlands since 1991 as part of a flowsheet in which 6 DWF (Dry Weather Flow) is treated by rotating biological contactors (RBCs), and constructed reed beds used to provide both tertiary treatment and stormwater treatment. The company now has over 50 such sites using this flowsheet. Dimensioning and effluent quality achievable is reported and data presented showing the performance of reed beds treating stormwater alone or in admixture with RBC effluent. After 8-10 years of operation the condition of a number of storm reed beds was assessed to determine the remaining asset life. The majority seem likely to achieve at least another five years of operation before further review is needed.

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Treatment of Combined Sewer Overflows at Small Wastewater Treatment Works by Constructed Reed Beds

Water Science & Technology ◽

10.2166/wst.1999.0182 ◽

1999 ◽

Vol 40 (3) ◽

pp. 357-364 ◽

Cited By ~ 3

Author(s):

M. B. Green ◽

J. R. Martin ◽

P. Griffin

Keyword(s):

Wastewater Treatment ◽

Sewage Treatment ◽

Aggregate Data ◽

High Rate ◽

Storm Events ◽

Tertiary Treatment ◽

Combined Sewer Overflows ◽

Reed Beds ◽

Combined Sewer ◽

Reed Bed

The performance of constructed reed beds is illustrated by examination of results of surveys from a sewage treatment works with storm treatment reed beds and another site with a combined storm and tertiary treatment reed bed. During surveys of the first system the average hydraulic loads were between 25 and 40 cm d−1 and removals of between 6.7 to 15.4 g m−2 d BOD5, 17.7 to 38.6 g m−2 d TSS, 0.43 to 0.99 g m−2 d NH4N and 0.63 to 0.76 g m−2 d TON were observed. A survey during a storm at the combined storm and tertiary treatment reed bed showed a hydraulic loading of 98 cm d−1 in the first 24 hr and removals of 12.6 g m−2 d BOD5, 29.9 g m−2 d TSS, 0.49 g m−2 d NH4N and a small increase in TON. The sustainability of the high rate of removal during storm events is ascribed to the longer intervals in which loadings are much lower. Samples taken by the regulator from the time of commissioning of 20 sites with combined storm and tertiary treatment reed beds, up to the end of May 1998 are examined. Three of these had operational problems not associated with storm treatment. The aggregate data for the remaining 17 sites (n=906 to 911) illustrate a level of performance matching that of sites with tertiary treatment systems, with averages of 2.2 mg l−1 BOD5, 3.0 mg l−1 TSS, 1.25 mg l−1 NH4N and 12.2 mg l−1 TON.

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Danish Experience with Emergent Hydrophyte Treatment Systems (EHTS) and Prospects in the Light of Future Requirements on Outlet Water Quality

Water Science & Technology ◽

10.2166/wst.1990.0184 ◽

1990 ◽

Vol 22 (3-4) ◽

pp. 65-72 ◽

Cited By ~ 12

Author(s):

H.-H. Schierup ◽

H. Brix

Keyword(s):

Wastewater Treatment ◽

Total Nitrogen ◽

Total Phosphorus ◽

Wastewater Treatment Plants ◽

Sewage Treatment ◽

Reed Beds ◽

Effluent Quality ◽

Multi Stage ◽

Run Off ◽

Stage System

Since 1983 approximately 150 full-scale emergent hydrophyte based wastewater treatment plants (reed beds) have been constructed in Denmark to serve small wastewater producers. The development of purification performance for 21 plants representing different soil types, vegetation, and hydraulic loading rates has been recorded. Cleaning efficiencies were typically in the range of 60-80% reduction for BOD, 25-50% reduction for total nitrogen, and 20-40% reduction for total phosphorus. The mean effluent BOD, total nitrogen and total phosphorus concentrations of the reed beds were 19 ± 10, 22 ± 9 and 6.7 ± 3.2 mg/l (mean ± SD), respectively. Thus, the general Danish effluent standards of 8 mg/l for N and 1.5 mg/l for P for sewage plants greater than 5,000 PE cannot be met by the present realised design of EHTS. The main problem observed in most systems is a poor development of horizontal hydraulic conductivity in the soil which results in surface run-off. Since the political demands for effluent quality will be more strict in the future, it is important to improve the performance of small decentral sewage treatment plants. On the basis of experiences from different types of macrophyte based and conventional low-technology wastewater treatment systems, a multi-stage system is suggested, consisting of sedimentation and sand filtration facilities followed by basins planted with emergent and submergent species of macrophytes and algal ponds.

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Constructed reed beds: appropriate technology for small communities

Water Science & Technology ◽

10.2166/wst.1995.0156 ◽

1995 ◽

Vol 32 (3) ◽

pp. 339-348 ◽

Cited By ~ 7

Author(s):

M. B. Green ◽

J. Upton

Keyword(s):

Sewage Treatment ◽

Appropriate Technology ◽

Great Promise ◽

High Quality ◽

Reed Beds ◽

Small Communities ◽

Operational Information ◽

Reed Bed ◽

Small Sites ◽

Very High

Reed bed treatment is put in the context of a major water company’s need to provide reliable, high quality, effluents from small sewage treatment works whilst seeking to minimise running costs. Design and operational information is given for reed bed applications in Severn Trent Water. Performance details are provided for application to secondary, tertiary and storm overflow treatment. The results give particular confidence in the system’s ability to deliver very high quality effluents when used for tertiary treatment, the company’s biggest application. Reed beds work well against less demanding criteria for secondary treatment at small sites and show great promise for storm overflow treatment.

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Does Botanical Diversity in Sewage Treatment Reed-Bed Sites Enhance Invertebrate Biodiversity?

International Journal of Ecology ◽

10.1155/2012/324295 ◽

2012 ◽

Vol 2012 ◽

pp. 1-9

Author(s):

Alan Feest ◽

Ian Merrill ◽

Philippa Aukett

Keyword(s):

Species Richness ◽

Sewage Treatment ◽

Conservation Value ◽

Diverse Range ◽

Reed Beds ◽

Terrestrial Invertebrate ◽

Invertebrate Species ◽

Invertebrate Biodiversity ◽

Botanical Diversity ◽

Reed Bed

(1) This study examines the effect of increasing botanical diversity, through reed-bed planting and maintenance regimes, on sewage treatment reed-bed invertebrate biodiversity and the possible enrichment of overall catchment biodiversity. (2) Reed-bed invertebrates were identified as a good indicator group of overall site biodiversity quality and were sampled at a range of sewage treatment reed-bed sites in the same geographical area between May and August 2006 (plus one natural reed-bed control site). Standardised water trapping and pitfall trapping techniques were employed throughout this sampling period. (3) Statistical analysis of the sampling results revealed that the number of plant species recorded was inversely related to terrestrial invertebrate species richness, species conservation value index and biomass within the study sites. For example, the natural reed-bed sampled had the highest botanical diversity but the lowest terrestrial invertebrate species richness. (4) This study has demonstrated that sewage treatment reed-beds support a diverse range of invertebrate species, some of them being of national conservation value. This suggests that sewage treatment reed-beds may be at least as biodiverse as naturally occurring reed-beds and will add to the overall biodiversity and ecohydrology of a catchment whilst saving energy.

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Advanced Nitrogen Removal by Rotating Biological Contactors, Recycle and Constructed Wetlands

Water Science & Technology ◽

10.2166/wst.1999.0614 ◽

1999 ◽

Vol 40 (4-5) ◽

pp. 383-390 ◽

Cited By ~ 1

Author(s):

P. Griffin ◽

P. Jennings ◽

E. Bowman

Keyword(s):

Sewage Treatment ◽

Treatment Facility ◽

Reed Beds ◽

Reducing Conditions ◽

In Series ◽

Rotating Biological Contactors ◽

Reed Bed ◽

Advanced Nitrogen Removal ◽

Oxidised Nitrogen ◽

Influent Flow

The sewage treatment facility at Himley comprises Rotating Biological Contactors (RBCs) and subsurface flow constructed reed beds in series. A recycle facility returns RBC effluent to the influent flow. Effluent total nitrogen (TN) has always been low since commissioning and the reasons were investigated. Denitrification was observed to occur in the primary settlement tank. High hydraulic loadings in the RBC biozone deteriorated BOD5 and TSS removal, but good nitrification was obtained. The relatively poor effluent from the RBC gave a carbon source allowing further denitrification through the reed beds. Ammonification caused an increase in ammoniacal nitrogen across the primary reed bed in summer. At this time strongly reducing conditions occurred within the reed beds which, in the absence of dissolved oxygen and oxidised nitrogen compounds, led to sulphate reduction and sulphide formation with odour generation. These problems were not observed at low winter temperature conditions. Effluent TN was always below 0 mg/l.

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Factors affecting the longevity of sub-surface horizontal flow systems operating as tertiary treatment for sewage effluent

Water Science & Technology ◽

10.2166/wst.2005.0303 ◽

2005 ◽

Vol 51 (9) ◽

pp. 127-135 ◽

Cited By ~ 35

Author(s):

D. Cooper ◽

P. Griffin ◽

P. Cooper

Keyword(s):

Domestic Wastewater ◽

Tertiary Treatment ◽

Reed Beds ◽

Factors Affecting ◽

Domestic Wastewater Treatment ◽

Weed Infestation ◽

The Common ◽

Common Problems ◽

Reed Bed ◽

Flow Distributor

Compared with other forms of domestic wastewater treatment, reed beds require very little in the way of operational and maintenance input. This is even more markedly the case with tertiary treatment systems (than with secondary treatment systems) where the necessary maintenance amounts to only a few days/year. Unfortunately, in practice this frequently results in them receiving little or no attention at all. Tertiary treatment reed beds are not a “fit and forget” solution but they are often treated this way because they are very forgiving and abuse-tolerant. After a number of years a few of these tertiary reed beds have deteriorated to an extent whereby they are close to failing to comply with the regulator's requirements. Severn Trent Water Ltd has recognised this situation and has committed a budget for a programme of reed bed maintenance. This work has started with a survey of the condition of their beds and particularly to determine the common problems and hence the maintenance regime required. Five main problems occurred either singly or in combination namely: (a) sludge deposition; (b) above surface flooding (partially caused by (a), (c), and (d)); (c) inlet flow distributor problems/clogging; (d) outlet collector problems/incorrect level; (e) weed infestation.

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Counting Fish: Environmental Benefits Calculation for Avoided Costs Analysis in Urban Water Use Efficiency Planning

Water Practice & Technology ◽

10.2166/wpt.2008.030 ◽

2008 ◽

Vol 3 (2) ◽

Author(s):

Katie Shulte Joung ◽

Mary Ann Dickinson

Keyword(s):

Water Conservation ◽

Economic Value ◽

Environmental Benefits ◽

Urban Water ◽

Environmental Benefit ◽

Conservation Programs ◽

Water Utility ◽

Water Savings ◽

Urban Water Use ◽

Use Efficiency

This report documents a project undertaken for the California Urban Water Conservation Council to create a method to calculate water utility avoided costs and assign economic value to the environmental benefits of raw water savings as a result of implementing urban water conservation programs. It is assumed that water savings associated with implementation of conservation programs can be quantified and represented as a reduction in the demand for water from a particular set of supply sources. This demand reduction may in turn result in a change to the availability of an environmental benefit provided by that source. Environmental valuation, as it is applied here, is relatively new and there are numerous complications, ambiguities, data gaps and differences of opinion in the application of the methodology. For that reason, this report should be considered a pioneering effort to put together all the required elements in a single coherent framework.

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Reed bed treatment systems for sewage treatment in the United Kingdom - the first 10 years’ experience

Water Science & Technology ◽

10.2166/wst.1995.0154 ◽

1995 ◽

Vol 32 (3) ◽

pp. 317-327 ◽

Cited By ~ 12

Author(s):

P. Cooper ◽

B. Green

Keyword(s):

Root Zone ◽

Sewage Treatment ◽

Horizontal Flow ◽

Water Industry ◽

Soil Systems ◽

Design Changes ◽

Flow Systems ◽

Group A ◽

Reed Bed ◽

The Uk

The UK Water Industry first became interested in Reed Bed Treatment Systems for sewage in 1985. Early problems were experienced with soil-based horizontal-flow systems of the Root Zone type. The problems were overcome by national co-ordination of a development programme and international co-operation by an EC Expert Contact Group. A number of different types of systems have now been developed and the systems are now being accepted. The paper reviews the development of these systems for secondary and tertiary treatment and nitrification and mentions development of systems for other forms of treatment. The design changes made to overcome the problems are described. These include the gradual move to the use of gravel-based systems because of the difficulty experienced with over-land flow in the soil systems. The sizing of the systems is described together with performance data for the original horizontal-flow and the more recently developed vertical-flow systems. Treatment at secondary and tertiary levels is illustrated and the potential for nitrification. Early problems with reed growth have been overcome by planting with port-grown seedlings. After 10 years the process is generally accepted by the Water Industry as an appropriate treatment for villages and there are now between 200 and 300 systems in operation.

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