The use of vertical flow constructed wetlands for on-site treatment of domestic wastewater: New Danish guidelines (original) (raw)
Related papers
The use of Vertical Flow Constructed Wetlands in Wastewater Treatment
Water Resources Management, 2017
Alternative to conventional (i.e., the commonly used biological plants) wastewater treatment systems are presented which are appropriate for small communities and settlements. These systems are the natural treatment systems. The emphasis here is given on vertical downflow flow constructed wetlands (VF CWs). First, advantages and disadvantages of these systems are presented compared to conventional systems. Applications in treating different types of wastewaters and various pollutants are summarized. Components, treatment processes and performance are also presented. General description of facility compartments, layout and operation is given. Design guidelines on recommended unit areas, organic loading rates and hydraulic loading rates from various EU countries for VF CW systems used in municipal wastewater treatment, and data on the efficiency of such systems are also presented. Maintenance and operation issues are discussed. Finally, investment and operation and maintenance costs are addressed based on data from full-scale facilities.
Water science and technology : a journal of the International Association on Water Pollution Research, 2005
The Danish Ministry of Environment and Energy has passed new legislation that requires the wastewater from single houses and dwellings in rural areas to be treated adequately before discharge into the aquatic environment. Therefore official guidelines for a number of onsite treatment solutions have been produced. These include guidelines for soakaways, biological sand filters, technical systems as well as different types of constructed wetland systems. This paper summarises briefly the guidelines for horizontal flow constructed wetlands, vertical flow constructed wetlands, and willow systems with no outflow and with soil infiltration. There is still a lack of a compact onsite solution that will fulfil the treatment classes demanding 90% removal of phosphorus. Therefore work is presently being carried out to identify simpler and robust P-removal solutions.
To foster the practical development of the constructed wetlands used for water quality enhancement in Turkey, 2 vertical subsurface flow pilot-scale constructed wetlands were implemented on the METU campus, Ankara, Turkey. Both of the wetlands were planted with Phragmites australis and operated identically at a flowrate of 3 m3.d 1 and a hydraulic loading rate (HLR) of 0.100 m.d 1, intermittently. The main objective of the research was to quantify the eect of dierent substrates (gravel and blast furnace granulated slag) on the nutrient removal performance of the constructed wetlands in the prevailing climate of Ankara. According to the monitoring study (July 2002-January 2003), concentration based average removal eciencies for the slag and gravel reed beds were as follows: TSS (64% and 62%), COD (49% and 40%), NH+ 4 -N (88% and 58%), TN (41% and 44%), TP (63% and 9%) and PO3 4 -P (60% and 4%). In general, the treatment performance of the slag system was better than that of the grave...
Waste Materials as Substrates in Vertical Flow Constructed Wetlands Treating Domestic Wastewater
Waste Management and the Environment IX, 2018
Vertical flow constructed wetlands (VFCW) are considered to be one of the most efficient type of wetlands and require a lesser footprint in comparison to other wetland types. Substrate is an important component of wetland. We used the common gravel (VFCW 1) and three waste materials: concrete (VFCW 2), slag concrete (VFCW 3) and coconut husk (VFCW 4) as substrates in experimental wetlands. All four experimental wetlands have been constructed in uPVC pipes, diameter and height of each VFCW was 89 mm and 1000 mm, respectively. A 15 mm diameter perforated pipe that penetrates to the wetland bottom was installed in each wetland for passive aeration. Canna indica, an ornamental plant was planted in all four wetlands. Pre-treated wastewater from a wastewater treatment plant was added manually to all VFCW. The maximum plant height observed was 78.7 cm in VFCW 1 while minimum plant height observed was 53.3 cm in VFCW 3. The four VFCW removed all monitored contaminants with good removal efficiencies during the 8 months monitoring period: suspended solids (79%, 74%, 74%, 54%); BOD (54%, 42%, 42%, 2%); COD (54%; 47%; 44%, 34%); ammonia-nitrogen (54%, 46%, 38%, 38%), ortho-phosphate (67%, 61%, 64%, 53%); and fecal coliforms (55%, 40%, 14%, 52%). DO levels increased for VFCW 1 and 4 and nitrate levels increased in all wetlands confirming the nitrification process. For the various waste materials used following were our observations: VFCW 2 performed the best for organic matter and ammonia-nitrogen removal while VFCW 3 outperformed others for phosphorus removal and VFCW 4 had the highest percentage of fecal coliforms removal.
Linnaeus Eco-Tech, 2019
The efficiency of pollution removal from municipal sewage in two vertical flow constructed wetlands consisting of gravel filters with surface area 4 x 5 m, depth 60 cm, covered by reed was evaluated over a period of two years. The flow of wastewater was about 50 mm per day. Wastewater underwent only mechanical treatment before reed bed B, but reed bed A was supplied with wastewater after biological treatment with activated sludge. Sewage was sampled before and after filtration every IO days. Measurements were made of sewage supply and discharge, precipitation and wastewater temperatures. The main indicator of efficiency was the elimination of suspended solids, carbon, nitrogen and phosphorus from the wastewater during filtration. The elimination of the pollution load was 2-25 g per square meter per day for the BOD 5 and 0-3.5 g per square meter per day for total nitrogen. Rates of pollution removal were between 2 and 4 times as high in bed B as in bed A. The rate ofBOD 5 removal and the coefficient k for BOD5 were strongly dependent on temperature for reed bed B; less so far for bed A. The difference between summer and winter indicates that the surface area of constructed wetland B should be 3 times bigger during winter to obtain the summer rate ofBOD 5 pollution removal in the climatic conditions ofNorth Poland (54a° N).
Seasonal assessment of experimental vertical-flow constructed wetlands treating domestic wastewater
Bioresource Technology, 2013
The aim of this work was to compare the impact of different design (aggregate size) and operational (contact time, empty time and chemical oxygen demand (COD) loading) variables on the long-term and seasonal performance of vertical-flow constructed wetland filters operated in tidal flow mode. Compliance was achieved regarding ammonia-nitrogen, nitrate-nitrogen and suspended solids (SS), and non-compliance concerning biochemical oxygen demand (BOD) and ortho-phosphatephosphorus. The filter with the highest COD loading performed the best regarding outflow COD concentration. Higher COD inflow concentrations had a significantly positive impact on the treatment performance for COD, ortho-phosphate-phosphorus and SS. The wetland with the largest aggregate size had the lowest mean nitrate-nitrogen outflow concentration. However, the results were similar regardless of aggregate size and resting time for most variables. Clear seasonal outflow concentration trends (low in summer) were recorded for COD, ammonia-nitrogen and nitrate-nitrogen. No filter clogging was observed.
Water Science and Technology, 2018
The German Association for Water, Wastewater and Waste e.V. (DWA) has published a new standard for the dimensioning, construction, and operation of constructed wetlands for treatment of domestic and municipal wastewater. The changes to the standard are based on a wide range of experience gained in recent years in Germany and Europe. For the first time ever, the standard has been officially translated and published in English. This paper summarizes the new standard for secondary treatment of domestic wastewater with classical one-stage unsaturated vertical flow (VF) wetlands, VF wetlands with lava sand for treatment of wastewater from combined sewer systems, and actively aerated VF and horizontal flow (HF) flow wetlands. Two-stage unsaturated VF wetlands treating raw wastewater (French VF wetlands), are also included in the new standard. HF wetlands are no longer described in the standard for secondary treatment of domestic wastewater. This does not exclude their application. Existing HF wetland systems in Germany may continue to be operated so long as effluent parameters are met and proper operations and maintenance is ensured. This paper gives an overview of the new design standard, including key information on wastewater type and loading, as well as primary attributes of each wetland design.
Turkish Journal of Engineering and Environmental Sciences, 2004
To foster the practical development of the constructed wetlands used for water quality enhancement in Turkey, 2 vertical subsurface flow pilot-scale constructed wetlands were implemented on the METU campus, Ankara, Turkey. Both of the wetlands were planted with Phragmites australis and operated identically at a flowrate of 3 m 3 .d −1 and a hydraulic loading rate (HLR) of 0.100 m.d −1 , intermittently. The main objective of the research was to quantify the effect of different substrates (gravel and blast furnace granulated slag) on the nutrient removal performance of the constructed wetlands in the prevailing climate of Ankara. According to the monitoring study (July 2002-January 2003), concentration based average removal efficiencies for the slag and gravel reed beds were as follows: TSS (64% and 62%), COD (49% and 40%), NH + 4-N (88% and 58%), TN (41% and 44%), TP (63% and 9%) and PO 3− 4-P (60% and 4%). In general, the treatment performance of the slag system was better than that of the gravel system.
Ecological Engineering, 2011
Hybrid constructed wetland systems have recently been used to treat wastewaters where high demand for removal of ammonia is required. However, these systems have not been used too often for small onsite treatment systems. This is because in many countries ammonia is not limited in the discharge from small systems. Hybrid systems have a great potential to reduce both ammonia and nitrate concentrations at the same time. In our study we employed a three-stage constructed wetland system consisting of saturated vertical-flow (VF) bed (2.5 m 2 , planted with Phragmites australis), free-drained VF bed (1.5 m 2 , planted with P. australis) and horizontal-flow (HF) bed (6 m 2 , planted with Phalaris arundinacea) in series. All wetlands were originally filled with crushed rock (4-8 mm). However, nitrification was achieved only after the crushed rock was replaced with sand (0-4 mm) in the free-drain wetland. Also, original size of crushed rock proved to be too vulnerable to clogging and therefore, in the first wetlands the upper 40 cm was replaced by coarser fraction of crushed rock (16-32 mm) before the second year of operation started. The system was fed with mechanically pretreated municipal wastewater and the total daily flow was divided into two batches 12 h apart. The evaluation of the results from the period 2007 to 2008 indicated that such a system has a great potential for oxidation of ammonia and reduction of nitrate. The ammonia was substantially reduced in the free-drained VF bed and nitrate was effectively reduced in the final HF bed. The inflow mean NH 4-N concentration of 29.9 mg/l was reduced to 6.5 mg/l with the average removal efficiency of 78.3%. At the same time the average nitrate-N concentration rose from 0.5 to only 2.7 mg/l at the outflow. Removal of BOD 5 and COD amounted to 94.5% and 84.4%, respectively, with respective average outflow concentrations of 10 and 50 mg/l. Phosphorus was removed efficiently despite the fact that the system was not aimed at P removal and therefore no special media were used. Phosphorus removal amounted in 2008 to 65.4%, but the average outflow concentration of 1.8 mg/l is still high. The results of the present study indicate very efficient performance of the hybrid constructed wetlands, but optimal loading parameters still need to be adjusted. The capital cost of the experimental system is comparable to the conventional on-site treatment plant but the operations and maintenance costs are about one third of the conventional plant.