Treatment of Hydroponics Wastewater Using Constructed Wetlands in Winter Conditions (original) (raw)
Related papers
Seasonal Applicability of Three Plant Constructed Wetlands for Nutrient Removal in Pilot Scale
2016
The main objective of this study was to compare the removal efficiency of nutrients using Lactuca sativa, Medicago sativa and Phragmites australis in subsurface flow constructed wetlands with horizontal flow. In order to test water quality, fabricated reactors designed and the plants cultivated in the soil while their root were inside the wastewater. A long time study carried out from spring till end of autumn (9 months) in order to evaluate the difference in removal rate based on the seasonal changes. The highest removal rate was during summer which followed by spring and autumn. Thus, the effect of plants on the removal efficiency of organic matter (COD, BOD), TSS and nutrient (P and TN) appeared to be dependent on the seasonal growth. Phragmites australis the most sensitive species in order the removal of nutrient from wastewater.
ChemEngineering
Cultural eutrophication stimulated by anthropogenic-derived nutrients represents one of most widespread water quality problems worldwide. Constructed wetlands (CWs) have emerged as an aesthetic, sustainable form of wastewater treatment, but, although they have shown adequate levels of organic matter removal in wastewaters, the effectiveness of nutrient removal has been less successful. An eleven-month monitoring program was undertaken in a horizontal subsurface flow CW (HSSF-CW) treating domestic wastewater from a village in Centre Region of Portugal, to evaluate the influence of climatic conditions (Continental-Mediterranean Climate region) and seasonal variations on removal. This CW uses gravel and sand as substrate and Phragmites australis as wetland plants. Samples were collected at the inlet and outlet from wetland bed and analyzed for pH, TN, Org-N, NH 4 +-N, NO x-N, TP and DP. The removal efficiencies (RE) of nitrogen and phosphorus compounds were relatively poor, but the results allow us to conclude that season had a significant (p < 0.05) effect on the RE of TN, NH 4 +-N, NO x-N, TP and DP, with higher values in warmest period (10.4%, 10.4%, 3.4%, 27.5% and 26.1%, respectively) than in coldest period (0%, −7.7%, −9.8%, 12.9% and 0%, respectively). Although lower hydraulic loading rate (HLR) generally resulted in better RE of all N and P compounds analyzed, no significant linear relationship was observed between these two variables. TN and NH 4 +-N concentrations in the effluent tend to significantly (p < 0.05) decrease with increasing respective incoming mass load rates for whole monitoring period and during spring-summer period, while the correlation between outlet TP concentrations and the inlet loading rate are not significant. The results indicate that the system is not effective for removal of nutrients, probably because it operated on overload and with a low hydraulic retention time (HRT) (average = 2.4 days). The results also showed that the RE of N and P followed seasonal trends, with higher values during spring-summer period.
Ecological Engineering, 2020
Uptake of nutrients as a removal process in constructed wetlands with horizontal subsurface flow (HF CWs) treating municipal wastewater is usually considered negligible. However, there is very low number of results which would confirm this assumption. The amount of nutrients sequestered in the aboveground biomass, and thus available for harvesting, is called standing stock and it is determined by both nutrient concentration in the biomass and biomass itself. The common values of standing stock vary in the range of 30-80 g N m −2 and 2-6 g P m −2 while inflow loadings of municipal wastewater are around 950 g N m −2 yr −1 and 350 g P m −2 yr −1. Under these conditions, the standing stock represents less than 10% of the nitrogen load and 5% of phosphorus load. Removal of nitrogen and phosphorus in HF CWs is usually low and therefore, the percentage of removed load by plant uptake is higher. Under the conditions of low loadings, i.e., less that 500 (200) g N m −2 yr −1 or 100 (50) g P m −2 yr −1 , the portion of removed nitrogen or phosphorus could be substantially higher. In our study, the combination of high standing stocks (> 100 g N m −2 and 10 g P m −2) supported primarily by high plant biomass and low inflow loadings was responsible for removal of up to 62% of nitrogen and 58% of phosphorus. The results of our study carried out in four HF CWs in the Czech Republic indicate that the direct role of plants in nutrient removal in HF CWs may be underestimated especially under conditions of low inflow loading and high plant biomass.
Using wetland plants in nutrient removal from municipal wastewater
International Journal of Hydrology Science and Technology, 2014
In this study, three wetland plant species (phragmites australis, typha and rush) were planted in separate cells to evaluate the proportion of total nitrogen (TN) and total phosphorus (TP) removal attributed to storage in plants. Four cells were considered for each plant to be tested in a completely randomised design having four replications. Results show that the uptakes of nutrients by rush, common reed and typha from the pilot system were 49.39% TKN; 17.98% P, 44.62% TKN; 13.22% P and 27.62% TKN; 9.46% P, respectively. The nutrient uptakes efficiency corresponding to common reed and typha were higher in above-ground compared to that of below-grounds; however, for rush, the nutrient uptake efficiency was higher in below-ground rather than in above-ground tissues. The results can be applied in plant species selection in the design of constructed wetlands in Isfahan as well as in optimising the performance of these systems.
Water Environment Research
9 Subsurface flow (SSF) constructed wetland (CW) treatment performance with 10 respect to organics (COD) and nitrogen (ammonium and nitrate) removal from domestic 11 (septic tank) wastewater (WW) is evaluated as affected by the presence of plants, 12 different substrate "rock" having a range of cation exchange capacities (CEC), laboratory 13 versus field conditions and use of synthetic as compared to actual wastewater. This first 14 paper considers the effects of plants on CW treatment in the field, while subsequent 15 papers consider the effects of synthetic versus actual WW and substrate in the laboratory 16 and field on treatment. 17 Each CW system was comprised of two beds (2.6 m long by 0.28 m wide and 18 deep filled with ~18 mm crushed lava rock) separated by an aeration tank connected in 19 series. The lava rock had a porosity of ~47% and a CEC of 4 meq/100gm. One pair of 20 CW systems was planted with cattails in May 2008, while an adjacent pair of systems 21 remained unplanted. Collected septic tank or synthesized WW was allowed to gravity 22 feed each CW system and effluent samples were regularly collected and tested for COD 23 and nitrogen species during four different time periods spanning November 2008 through 24 June 2009. These effluent concentrations were tested for statistical differences at the 25 95% level during individual time periods as well as the 6-month period as a whole. 26 Overall organic removal from domestic WW was 78.8% and 76.1% in the planted 27 and unplanted CW systems, respectively, while ammonium removal was 94.5% and 28 90.2%, respectively. Similarly, organic removal from the synthetic WW of equivalent 29 strength was 88.8% and 90.1% for planted and unplanted CW systems, respectively, 30 while ammonium removal was 96.9% and 97.3%, respectively. 31 32
Journal of Environmental Engineering and Science, 2007
We studied the contribution of artificial aeration, loading rate, and macrophyte species on pollutant removal in horizontal subsurface flow constructed wetlands (HSSFCWs) treating reconstituted trout farm wastewater. Twelve 1 m 2 mesocosms located in a controlled greenhouse environment were used to test two species of macrophytes (Phragmites australis, Typha angustifolia), three loading rates (30, 60, and 90 L·m −2 ·d −1 ), and presence or absence of artificial aeration at the intermediate loading rate. There was no effect of any variable (macrophytes, loading, aeration) on total suspended solids (TSS) or chemical oxygen demand (COD) removal. Artificial aeration improved nitrogen removal while higher loading rates diminished removal of nitrogen and phosphorus. Macrophytes improved nitrogen and phosphorus removal, but this effect varied depending on loading rates and presence or absence of artificial aeration. We found no differences between Phragmites and Typha for treatment of trout fish farm wastewater. Under summer conditions, our results suggest that artificial aeration could be used to improve nitrogen removal by HSSFCWs.
Simultaneous Removal of Nitrate and Sulfate from Greenhouse Wastewater by Constructed Wetlands
Journal of Environmental Quality, 2013
The user has requested enhancement of the downloaded file. All in-text references underlined in blue are linked to publications on ResearchGate, letting you access and read them immediately. 1256 This study evaluated the effectiveness of C-enriched subsurfaceflow constructed wetlands in reducing high concentrations of nitrate (NO 3 -) and sulfate (SO 4 2-) in greenhouse wastewaters. Constructed wetlands were filled with pozzolana, planted with common cattail (Typha latifolia), and supplemented as follows: (i) constructed wetland with sucrose (CW+S), wetland units with 2 g L -1 of sucrose solution from week 1 to 28; (ii) constructed wetland with compost (CW+C), wetland units supplemented with a reactive mixture of compost and sawdust; (iii) constructed wetland with compost and no sucrose (CW+CNS) from week 1 to 18, and constructed wetland with compost and sucrose (CW+CS) at 2 g L -1 from week 19 to 28; and (iv) constructed wetland (CW). During 28 wk, the wetlands received a typical reconstituted greenhouse wastewater containing 500 mg L -1 SO 4 2and 300 mg L -1 NO 3 -. In CW+S, CW+C, and CW+CS, appropriate C:N ratio (7:3.4) and redox potential (-53 to 39 mV) for denitrification resulted in 95 to 99% NO 3 removal. Carbon source was not a limiting factor for denitrification in C-enriched constructed wetlands. In CW+S and CW+CS, the dissolved organic carbon (DOC)/SO 4 2ratios of 0.36 and 0.28 resulted in high sulfate-reducing bacteria (SRB) counts and high SO 4 2removal (98%), whereas low activities were observed at DOC/SO 4 2ratios of 0.02 (CW) to 0.11 (CW+C, CW+CNS). On week 19, when organic C content was increased by sucrose addition in CW+CS, SRB counts increased from 2.80 to 5.11 log[CFU+1] mL -1 , resulting in a level similar to the one measured in CW+S (4.69 log[CFU+1] mL -1 ). Consequently, high sulfate reduction occurred after denitrification, suggesting that low DOC (38-54 mg L -1 ) was the limiting factor. In CW, DOC concentration (9-10 mg L -1 ) was too low to sustain efficient denitrification and, therefore, sulfate reduction. Furthermore, the high concentration of dissolved sulfides observed in CW+S and CW+CS treated waters were eliminated by adding FeCl 3 .
Effect of different plant species in pilot constructed wetlands for wastewater reuse in agriculture
Journal of Agricultural Engineering, 2013
In this paper the first results of an experiment carried out in Southern Italy (Sicily) on the evapotranspiration (ET) and removal in constructed wetlands with five plant species are presented. The pilot plant used for this study is made of twelve horizontal sub-surface flow constructed wetlands (each with a surface area of 4.5 m 2) functioning in parallel, and it is used for tertiary treatment of part of the effluents from a conventional municipal wastewater treatment plant (trickling filter). Two beds are unplanted (control) while ten beds are planted with five different macrophyte species: Cyperus papyrus, Vetiveria zizanoides, Miscanthus x giganteus, Arundo donax and Phragmites australis (i.e., every specie is planted in two beds to have a replication). The influent flow rate is measured in continuous by an electronic flow meter. The effluent is evaluated by an automatic system that measure the discharged volume for each bed. Physical, chemical and microbiological analyses were carried out on wastewater samples collected at the inlet of CW plant and at the outlet of the twelve beds. An automatic weather station is installed close to the experimental plant, measuring air temperature, wind speed and direction, rainfall, global radiation, relative humidity. This allows to calculate the reference Evapotranspiration (ET0) with the Penman-Monteith formula, while the ET of different plant species is measured through the water balance of the beds. The first results show no great differences in the mean removal performances of the different plant species for TSS, COD and E.coli, ranged from, respectively, 82% to 88%, 60% to 64% and 2.7 to 3.1 Ulog. The average removal efficiency of nutrient (64% for TN; 61 for NH4-N, 31% for PO4-P) in the P.australis beds was higher than that other beds. From April to November 2012 ET measured for plant species were completely different from ET0 and ETcontrol, underlining the strong effect of vegetation. The cumulative evapotranspiration highest value was measured in the CWs vegetated with P.australis (4,318 mm), followed by A.donax (2,706 mm), V.zizanoides (1,904), M.giganteus (1,804 mm), C.papyrus (1,421 mm).
Effect of loading rate on performance of constructed wetlands treating an anaerobic supernatant
Water Science and Technology, 2007
The effect of organic loading, season and plant species on the treatment of fish farm effluent was tested using three-year old mesocosm wetland systems. During one year, nine 1 m2 mesocosms (horizontal subsurface flow), located in a controlled greenhouse environment, were fed with a reconstituted fish farm effluent containing a high fraction of soluble components (1,600 μS/cm and in mg/L: 230±80 COD, 179±60 sCOD, 100±40 TSS, 37±7 TKN, 14±2 TP). Combinations of three hydraulic loading rates (30, 60 and 90 L.m−2 d−1) and two plant species (Phragmites australis, Typha angustifolia) and an unplanted control were tested for treatment performance and hydraulic behaviour. Loadings higher than 15 g COD m−2 d−1 resulted in a net decrease of hydraulic performances (generation of short circuiting) coupled with low TKN removal. Maximal TKN removal rates (summer: 1.2, winter: 0.6 g.m−2 d−1) were reached in planted units. In all mesocosms, phosphorus was removed during summer (maximal removal rat...