Hybrid constructed wetlands for the treatment of wastewater from a fertilizer manufacturing plant: Microcosms and field scale experiments (original) (raw)
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COMPARISON OF TREATMENT PERFORMANCE BETWEEN CONSTRUCTED WETLANDS WITH DIFFERENT PLANTS
Constructed wetlands have gained much importance for treating domestic, industrial and agricultural wastes and are considered as an effective secondary or tertiary treatment method. The main characteristics affect the removal efficiency of constructed wetland are the vegetation type, hydraulic residence time and substrate. The aim of the present study is to examine effect of vegetation type on organic and nutrient removal under varying hydraulic residence time in constructed wetlands. With this in mind, we have designed, constructed and operated two pilot-scale horizontal subsurface flow constructed wetlands having two different wetland vegetation plants in our open-air laboratory receiving pre-treated domestic wastewater by varying hydraulic residence time as 2, 4, 6 and 8 days. The influent wastewater is rich in orgnic matter with high variability presence of nutrients. In the first unit, the removal efficiency of COD, BOD, TN, and TP was increased from 39 to 69%, 29 to 56%, 23 to 45% and 25 to 75% when there was an increase in HRT from 2 days to 8 days respectively. In the second unit, the removal efficiency of COD, BOD, TN, and TP was increased from 31 to 68%, 25 to 52%, 26 to 36% and 40 to 77% when there was an increase in HRT from 2 days to 8 days respectively. It was found that vegetation type influenced concentration reduction. A 6-day hydraulic residence time is suggested for an acceptable level of treatment in these systems.
Ecological Engineering, 2020
The universalization and decentralization of wastewater treatment is one of the greatest challenges faced in Brazil. In this context, Constructed Wetlands (CWs) may be considered environment friendly and economically viable alternative for geographically remote locations, having fewer financial resources and infrastructure. During the last years, studies have investigated different configurations aiming to increase the capacity of CW to remove nutrients, mainly phosphorus (P) and reinforced its importance in ecological and landscape contexts. Thus, the present study evaluated the performance of a hybrid system combining Floating, Vertical and Horizontal Flow CWs to treat urban wastewaters. A removable adsorbent barrier was developed to improve the removal of P and a polyculture with ornamental plants was used to add landscape potential. The obtained results showed a promising nutrients removal capacity of the hybrid system, with mean removal rates of 94.0% for total P, 93.8% for ammonium nitrogen (N−NH 3), 93.8% for total nitrogen (N), 80.0% for dissolved organic carbon (DOC), 84.0% for biochemical oxygen demand (BDO 5), 77.0% for chemical oxygen demand (COD) and 99.7% for turbidity. The integrated system kept its ability to remove pollutants during the 11 months of operation (January to December 2019), without substrate saturation, and also maintaining P values within the limits allowed by current Brazilian (CONSEMA Resolution 355/17 (3 mg L −1)) and international legislation (UWTD 91/271/EEC (2 mg L −1)). The landscape benefits were extremely positive mainly due to the flowering of Canna generalis and its greater biomass production. By crossing the biomass data and the accumulation of nutrients in the tissues of the aerial part it was possible to verify that the contribution of the plants in the N removal from the system reached 8.08% while the P decrease attained 17.92% in the horizontal sub-surface flow constructed wetland (HSSFCWs). Therefore, the developed system enabled an efficient removal of nutrients throughout the monitoring period, enhancing the wastewater quality and potentializing its reuse for different purposes. Witthayaphirom et al., 2019; Lin et al., 2020). Thus, it is necessary to use processes that make it possible to reduce the eutrophic potential and encourage the reuse of water. In this sense, CWs have been considered interesting options for decentralized
Ecological Engineering, 2015
Constructed wetlands (CWs) are engineered systems that attained much attention as a feasible wastewater treatment technology particularly for small communities. It has been widely considered that the type of vegetation and hydraulic retention time (HRT) are two key intervening ingredients which directly influence the performance of CW. This study aims to compare the efficiency of a laboratory scale sub-surface hybrid constructed wetland (SS-HCW) for domestic wastewater treatment planted with different plants species (Brachiaria reptans and Trianthema portulacastrum) at different hydraulic retention times. Our findings revealed that the CW planted with T. portulacastrum showed higher total suspended solids (TSS), total dissolved solids (TDS), SO 4 2À , PO 4 3À , NO 3 À and NO 2
Constructed wetlands for wastewater treatment
Wetlands and Natural …, 2006
The first experiments using wetland macrophytes for wastewater treatment were carried out in Germany in the early 1950s. Since then, the constructed wetlands have evolved into a reliable wastewater treatment technology for various types of wastewater. The classification of constructed wetlands is based on: the vegetation type (emergent, submerged, floating leaved, free-floating); hydrology (free water surface and subsurface flow); and subsurface flow wetlands can be further classified according to the flow direction (vertical or horizontal). In order to achieve better treatment performance, namely for nitrogen, various types of constructed wetlands could be combined into hybrid systems.
Microcosm Wetlands for Wastewater Treatment with Different Hydraulic Loading Rates and Macrophytes
Journal of Environment Quality, 2002
Constructed wetlands (CW) usually require large land areas for ties. Applying any traditional wastewater treatment treating wastewater. This study evaluated the feasibility of applying system to purify these reservoirs would be expensive. CW with less land requirement by operating a group of microcosm wetlands at a hydraulic retention time (HRT) of less than 4 d in In addition, the annual water temperature in southern southern Taiwan. An artificial wastewater, simulating municipal waste-Taiwan ranges from 20 to 32ЊC and under such warm water containing 200 mg L Ϫ1 of chemical oxygen demand (COD), weather conditions treating the polluted water with a 20 mg L Ϫ1 of NH ؉ 4-N (AN), and 20 mg L Ϫ1 of PO 3Ϫ 4-P (OP), was the wetland system becomes a reasonable option. inflow source. Three emergent plants [reed, Phragmites australis In our initial study, we found that a CW system effec-(Cav.) Trin. ex Steud.; water primrose, Ludwigia octovalvis (Jacq.) tively removed nutrients from highly polluted river wa-P.H. Raven; and dayflower, Commelina communis L.] and two floatter (Jing et al., 2001). Removal efficiencies for organics, ing plants [water spinach, Ipomoea aquatica Forssk.; and water letammonia nitrogen (AN), and orthophosphate (OP) tuce, Pistia stratiotes L.] plants were tested. The planted systems were influenced by the health and growth rate of the showed more nutrient removal than unplanted systems; however, macrophytes. The presence of the macrophytes enthe type of macrophytes in CW did not make a major difference in treatment. At the HRTs of 2 to 4 d, the planted system maintained hances several functions in the CW system: assisting greater than 72, 80, and 46% removal for COD, AN, and OP, respecsolids sedimentation, reducing algae production, providtively. For AN and OP removal, the highest efficiencies occurred at ing surface area for microbial growth, improving nutrithe HRT of 3 d, whereas maximum removal rates for AN and OP ent uptake, and releasing oxygen (Brix, 1997). Comoccurred at the HRT of 2 d. Both removal rates and efficiencies were monly used macrophytes in CW systems in the United reduced drastically at the HRT of 1 d. Removals of COD, OP, and States are bulrushes (Scirpus spp.), cattails (Typha spp.), AN followed first-order reactions within the HRTs of 1 to 4 d. The and water hyacinth [Eichhornia crassipes (Mart.) Solms] efficient removals of these constituents obtained with HRT between (Brown and Reed, 1994). However, it was necessary to 2 and 4 d indicated the possibility of using a CW system for wasteidentify domestic macrophytes for potential use in our water treatment with less land requirement. CW system. The treatment efficiency of pollutants in a CW system is usually improved by decreasing the hydraulic loading: Abbreviations: AN, ammonia nitrogen; CCE, surface-covered control experimental system; COD, chemical oxygen demand; CW, constructed wetlands; CW-Co, constructed wetlands planted with day-Shuh-Ren Jing, Ying-Feng Lin, and Der-Yuan Lee, Department of flower; CW-Ip, constructed wetlands planted with water spinach; CW-Environmental Engineering and Health, and Tze-Wen Wang, Depart-Lu, constructed wetlands planted with water primrose; CW-Ph, conment of Pharmacy, Chia
Water research, 2013
The hybrid systems were developed in the 1960s but their use increased only during the late 1990 s and in the 2000s mostly because of more stringent discharge limits for nitrogen and also more complex wastewaters treated in constructed wetlands (CWs). The early hybrid CWs consisted of several stages of vertical flow (VF) followed by several stages of horizontal flow (HF) beds. During the 1990 s, HF-VF and VF-HF hybrid systems were introduced. However, to achieve higher removal of total nitrogen or to treat more complex industrial and agricultural wastewaters other types of hybrid constructed wetlands including free water surface (FWS) CWs and multistage CWs have recently been used as well. The survey of 60 hybrid constructed wetlands from 24 countries reported after 2003 revealed that hybrid constructed wetlands are primarily used on Europe and in Asia while in other continents their use is limited. The most commonly used hybrid system is a VF-HF constructed wetland which has been u...
Constructed wetlands for the treatment of organic pollutants
Journal of Soils and Sediments, 2003
Constructed Wetlands Review Articles 2. Floating-leaved macrophytes are rooted in submersed sediments in water depths of approximately 0.5 to 3 m and posses either floating or slightly aerial leaves (e.g. Nymphaea odorata, Nuphar lutea). 3. Submerged macrophytes occur at all depths within the photic zone. Vascular angiosperms (e.g. Myriophyllum spicatum, Ceratophyllum demersum) can occur in water up to 10 m deep (1 atm hydrostatic pressure) but non vascular macro-algae can occur to the lower limit of the photic zone (up to 200 m, e.g. Rhodophyceaered algae). 4, Freely floating macrophytes are not rooted to the substratum; they float freely on or in the water column and are usually restricted to nonturbulent, protected areas (e.g. Lemna minor, Spirodela polyrhiza, Eichhornia crassipes). 1 Wetlands for Water Treatment (Constructed wetlands, Wetland treatment systems) Natural wetlands have been used for wastewater treatment for centuries. In many cases, however, the reasoning behind this use was disposal, rather than treatment and the wetland simply served as a convenient recipient that was closer than the nearest river or other waterway (Reddy and Smith 1987). Naturals wetlands are still used for wastewater treatment (e.g. Kadlec and Tiltion 1979), but since 10 to 20 years the use of constructed wetlands has become more popular and effective around the world (e.g. Reddy and Smith 1987; Kadlec and Knight 1996; Cooper et al. 1996). Constructed wetland treatment systems are engineered systems designed and constructed to utilize the natural processes involving wetland vegetation, soils, and their associated microbial assemblages to assist in treating wastewater. They are designed to take advantage of many of the same processes that occur in natural wetlands, but do so within a more controlled environment. Constructed wetlands for wastewater treatment may be classified according to Brix (1994) to the life form of the dominating macrophytes into 1. Free-floating macrophyte-based systems, 2. Submerged macrophyte-based systems, and 3. Rooted emergent macrophyte-based systems. and according to the water flow different rooted emergent systems are distinguished into 9 surface flow systems, 9 horizontal subsurface flow systems, and 9 vertical subsurface flow systems.
Multi-year research on the use of constructed wetlands for advanced wastewater treatment
2005
Abstract. The use of constructed wetlands for tertiary wastewater treatment is emerging as a cost-effective wastewater treatment technology. Constructed wetlands are theoretically designed and operated so that the target constituents have ample time to interact with wetland substrates and microbiota to effect constituent removal necessary to achieve water quality discharge limits. Unfortunately, engineering natural systems is complicated and operational criteria are poorly defined. Long-term research is needed that compares design configurations as well as performance since each constructed wetland system is subjected to a variety of stochastic events (i.e. wind speed and direction, sedimentation due to pulsed rain events, plant dispersal and plant succession). The 650-acre constructed wetland system in Augusta, Georgia was developed in three phases, beginning with a 60-acre pilot study that evaluated use of the technology for ammonia and BOD removal. The pilot study was operated fr...
Pollution, 2023
Constructed wetland systems (CWs) are low-cost natural treatment systems for various types of influents. Although mainly the natural wetlands are soil-based, the constructed wetlands have been traditionally built using aggregate media. The performance of four types of available soils in Chhattisgarh was studied as the filter media in the horizontal subsurface flow-constructed wetland (HSFCW). Fourteen pilot-scale CW units with different soil types (entisol, vertisol, alfisol, inceptisol, and stone aggregate) and plant types (Canna indica and Typha latifolia) were used to treat domestic wastewater (WW). One set of each soil base reactor was planted with Canna indica and Typha latifolia, and one was kept blank (unplanted). All soils and plants are easily available. The reactors received primary wastewater in batch loads with WW loading for six hours to maintain aerobic conditions. The residence time of WW was 48 hours, and the applied hydraulic loading rate (HLR) was based on soil and aggregate. According to the findings, the planted HSFCW was more effective than the unplanted system. The results show that the wetland constructed on the treatment efficiency of the soil base has excellent potential to treat WW, with both plants.
Wetlands for wastewater treatment and subsequent recycling of treated effluent: a review
Environmental Science and Pollution Research
Due to water scarcity challenges around the world, it is essential to think about non-conventional water resources to address the increased demand in clean freshwater. Environmental and public health problems may result from insufficient provision of sanitation and wastewater disposal facilities. Because of this, wastewater treatment and recycling methods will be vital to provide sufficient freshwater in the coming decades, since water resources are limited and more than 70% of water are consumed for irrigation purposes. Therefore, the application of treated wastewater for agricultural irrigation has much potential, especially when incorporating the reuse of nutrients like nitrogen and phosphorous, which are essential for plant production. Among the current treatment technologies applied in urban wastewater reuse for irrigation, wetlands were concluded to be the one of the most suitable ones in terms of pollutant removal and have advantages due to both low maintenance costs and required energy. Wetland behavior and efficiency concerning wastewater treatment is mainly linked to macrophyte composition, substrate, hydrology, surface loading rate, influent feeding mode, microorganism availability, and temperature. Constructed wetlands are very effective in removing organics and suspended solids, whereas the removal of nitrogen is relatively low, but could be improved by using a combination of various types of constructed wetlands meeting the irrigation reuse standards. The removal of phosphorus is usually low, unless special media with high sorption capacity are used. Pathogen removal from wetland effluent to meet irrigation reuse standards is a challenge unless supplementary lagoons or hybrid wetland systems are used.