Constructed reed beds: appropriate technology for small communities

1995 ◽  
Vol 32 (3) ◽  
pp. 339-348 ◽  
Author(s):  
M. B. Green ◽  
J. Upton

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.

2012 ◽  
Vol 2012 ◽  
pp. 1-9
Author(s):  
Alan Feest ◽  
Ian Merrill ◽  
Philippa Aukett

(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.


1999 ◽  
Vol 40 (4-5) ◽  
pp. 383-390 ◽  
Author(s):  
P. Griffin ◽  
P. Jennings ◽  
E. Bowman

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.


2000 ◽  
Vol 41 (1) ◽  
pp. 73-76 ◽  
Author(s):  
T. Gschlößl ◽  
H. Stuible

Constructed wetlands in many different forms have been used in the rural regions of Bavaria for sewage treatment for several years. In 1998 the Abwassertechnische Vereinigung (ATV) published unique design and treatment guidelines with the aim to operate reed bed plants up to a size of 1000 p.e. according to technical standards concerning the oxidation of BOD and COD which will be presented. The treatment capacities of two reed bed plants in Bavaria which were constructed in accordance with these technical standards have been characterised by a high quality effluent during the first ten years of performance. This was especially the case during summer. After more than ten years the plant of See showed a reduced treatment quality. Practical results of investigations on the absorption of heavy metals and other hazardous organic compounds in the substrate of the two reed bed plants will demonstrate that only copper and zinc are significantly stored in the material after more than ten years of performance. The possibility of advanced sewage treatment in constructed wetlands will be discussed.


1998 ◽  
Vol 38 (3) ◽  
pp. 143-150
Author(s):  
P. Griffin ◽  
C. Pamplin

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.


1999 ◽  
Vol 40 (3) ◽  
pp. 357-364 ◽  
Author(s):  
M. B. Green ◽  
J. R. Martin ◽  
P. Griffin

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.


Author(s):  
C. O. Jung ◽  
S. J. Krause ◽  
S.R. Wilson

Silicon-on-insulator (SOI) structures have excellent potential for future use in radiation hardened and high speed integrated circuits. For device fabrication in SOI material a high quality superficial Si layer above a buried oxide layer is required. Recently, Celler et al. reported that post-implantation annealing of oxygen implanted SOI at very high temperatures would eliminate virtually all defects and precipiates in the superficial Si layer. In this work we are reporting on the effect of three different post implantation annealing cycles on the structure of oxygen implanted SOI samples which were implanted under the same conditions.


Author(s):  
M. Iwatsuki ◽  
S. Kitamura ◽  
A. Mogami

Since Binnig, Rohrer and associates observed real-space topographic images of Si(111)-7×7 and invented the scanning tunneling microscope (STM),1) the STM has been accepted as a powerful surface science instrument.Recently, many application areas for the STM have been opened up, such as atomic force microscopy (AFM), magnetic force microscopy (MFM) and others. So, the STM technology holds a great promise for the future.The great advantages of the STM are its high spatial resolution in the lateral and vertical directions on the atomic scale. However, the STM has difficulty in identifying atomic images in a desired area because it uses piezoelectric (PZT) elements as a scanner.On the other hand, the demand to observe specimens under UHV condition has grown, along with the advent of the STM technology. The requirment of UHV-STM is especially very high in to study of surface construction of semiconductors and superconducting materials on the atomic scale. In order to improve the STM image quality by keeping the specimen and tip surfaces clean, we have built a new UHV-STM (JSTM-4000XV) system which is provided with other surface analysis capability.


1990 ◽  
Vol 22 (3-4) ◽  
pp. 65-72 ◽  
Author(s):  
H.-H. Schierup ◽  
H. Brix

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.


1995 ◽  
Vol 32 (3) ◽  
pp. 317-327 ◽  
Author(s):  
P. Cooper ◽  
B. Green

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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