scholarly journals Effect of HRT and seasons on the performance of pilot-scale horizontal subsurface flow constructed wetland to treat rural wastewater

Author(s):  
R. Shruthi ◽  
G. P. Shivashankara

Abstract To find the effect of Hydraulic Retention Time (HRT) and seasons on the performance of horizontal subsurface flow constructed wetland (HSSF CW) in treating rural wastewater, a pilot scale unit 2.5 m × 0.4 m × 0.3 m size bed planted with a Typha latifolia and Phragmites australis was operated for a 12-month duration. During the study 2, 4, 6, 8, and 10 days of HRT were maintained in winter, summer, and rainy seasons. The removal efficiency obtained was ranges from 62.09 to 87.23% for Chemical Oxygen Demand, 69.58% to 93.32% for Biochemical Oxygen Demand5 (BOD), 31.55% to 59.89% for Ammonia Nitrogen (NH4-N), 15.18% to 52.90% for Total Kjeldahl Nitrogen (TKN), 21.02% to 50.21% for Phosphate Phosphorus (PO43− P), 19.82% to 48.23% for, Total phosphorus (TP), 74.93% to 93.10% for Faecal Coliform (FC) and 69.93% to 90.23% Total Coliform (TC). Overall, results showed that the performance of the unit was good. For statistical analysis two way ANOVA test followed by the Tukey test was used with a 95% level of significance. It was observed that the removal efficiency of the pollutants were increased with an increase in HRT. HRT of 6 days found as adequate for significant removal of organic matter (COD and BOD). Seasonal removal efficiencies followed the order of summer > rainy > winter for all the parameters, but the difference was not statistically significant.

Author(s):  
R. Shruthi ◽  
G. P. Shivashankara

Abstract In rural country like India, low cost and decentralized treatment unit like vertical subsurface flow constructed wetland (VSSF CW) can be reflected as a novel wastewater system. In this concern a pilot-scale VSSF CW unit of size 0.92 m × 0.92 m × 0.85 m bed planted with a Typha latifolia and Phragmites australis was operated for a 12-month duration to treat the simulated rural wastewater. During the operation, a constant head arrangement was done to maintain a continuous flow to achieve 5 different Hydraulic Retention Time (HRT) of 2, 4, 6, 8 and 10 days in each seasons such as winter, summer and rainy to investigate the performance of unit under different retention time. Reactor showed optimum removal efficiency at 6 days HRT at 12.5 cm/day Hydraulic Loading Rate (HLR) for organic matter removal. Both macrophytes and microbial biomass of filter media were effectively treated the rural wastewater. Average removal efficiency of the reactor during entire study were 64.73%–88.80% for Chemical Oxygen Demand, 74.96%–95.34% for Biochemical Oxygen Demand, 40.13%–79.45% for Ammonia Nitrogen, 25.36%–65.65% for Total Kjeldahl Nitrogen, 22.86%–58.48% for Phosphate phosphorus, 23.50%–55.45% for Total phosphorous, 74.91%–98.59% for Faecal Coliforms and 71.14%–95.31% for Total Coliforms respectively. Two-way ANOVA followed by post hoc Tukey's test showed that HRT had a significant impact on removal efficiency but not the season. Overall performance of the unit was good and study suggested that VSSF CW can be an smart alternative technology to treat rural wastewater before the final disposal.


2010 ◽  
Vol 37 (3) ◽  
pp. 496-501 ◽  
Author(s):  
K.N. Njau ◽  
M. Renalda

A horizontal subsurface flow constructed wetland (HSSFCW) was employed to remove tannins from the effluent of a tannins extracting company. Two HSSFCW cells with hydraulic retention time (HRT) of 9 d and packed with limestone were used. One cell without macrophytes was used as a control, while the second cell was planted with Phragmites mauritianus . Results indicated that HSSFCW was capable of treating tannin wastewater that has been seeded with primary facultative pond sludge. Tannins and chemical oxygen demand (COD) removal efficiency of 95.9% and 90.6% with outlet concentration of 27 mg/L and 86 mg/L, respectively, were obtained in the planted cell; while the tannins and COD removal efficiency of 91.1% and 89.5% with outlet concentration of 57 mg/L and 96 mg/L, respectively, were obtained in the control cell.


2020 ◽  
Author(s):  
Gede H Cahyana

Activated sludge is a wastewater treatment reactor widely applied for hospital. The reactor requires a mechanical aerator as a source of oxygen. At the same time, Subsurface Flow Constructed Wetland is rarely used. Both types of reactors utilize microbes in reducing pollutants of wastewater. The role of microbes in activated sludge is taken over by microbes that grow in the root zone of Typha latifolia and Vetiver sp. Two laboratory scale reactors were made to get serial data on the performance of the two plants in treating hospital wastewater. The result, the removal efficiency of COD on Q1 = 0.13 l/h and COD on Q2 = 0.43 l/h for Typha latifolia plants were 87.71% and 67.61%. On Vetiver sp. plants were 90,07% and 68,32%. The removal efficiency of BOD5 on Q1 = 0.13 l/h and Q2 = 0.43 l/h for Typha latifolia plants were 90.00% and 71.7%. On Vetiver sp. plants were 91.69% and 73.29%. The efficiency of Total Kjeldahl Nitrogen removal (TKN) Q1 = 0.13 l/h and Q2 = 0.43 l/h for Typha latifolia plants were 91.27% and 61.54%, whereas in Vetiver sp. plants were 92.01% and 62.68%. Horizontal Subsurface Flow Constructed Wetland is capable and feasible for hospital wastewater treatment.


2017 ◽  
Vol 77 (4) ◽  
pp. 988-998 ◽  
Author(s):  
Tadesse Alemu ◽  
Andualem Mekonnen ◽  
Seyoum Leta

Abstract In the present study, a pilot scale horizontal subsurface flow constructed wetland (CW) system planted with Phragmites karka; longitudinal profile was studied. The wetland was fed with tannery wastewater, pretreated in a two-stage anaerobic digester followed by a sequence batch reactor. Samples from each CW were taken and analyzed using standard methods. The removal efficiency of the CW system in terms of biological oxygen demand (BOD), chemical oxygen demand (COD), Cr and total coliforms were 91.3%, 90%, 97.3% and 99%, respectively. The removal efficiency for TN, NO3− and NH4+-N were 77.7%, 66.3% and 67.7%, respectively. Similarly, the removal efficiency of SO42−, S2− and total suspended solids (TSS) were 71.8%, 88.7% and 81.2%, respectively. The concentration of COD, BOD, TN, NO3−N, NH4+-N, SO42 and S2− in the final treated effluent were 113.2 ± 52, 56 ± 18, 49.3 ± 13, 22.75 ± 20, 17.1 ± 6.75, 88 ± 120 and 0.4 ± 0.44 mg/L, respectively. Pollutants removal was decreased in the first 12 m and increased along the CW cells. P. karka development in the first cell of CW was poor, small in size and experiencing chlorosis, but clogging was higher in this area due to high organic matter settling, causing a partial surface flow. The performance of the pilot CW as a tertiary treatment showed that the effluent meets the permissible discharge standards.


2014 ◽  
Vol 1073-1076 ◽  
pp. 965-969 ◽  
Author(s):  
Ahmed Mohammed Osman ◽  
Xi Wu Lu

In this study, the performance treatment of horizontal subsurface flow constructed wetland (HSFCW) was evaluated. The HSFCW built as a tertiary treatment process after the biological reactors to improve the effluent quality. The HSFCW system was operated with different hydraulic loading rates (HLRs) ranged from 0.15 to 0.333 m3/ (m2.d) to assess their influence on removal efficiency. During the system operation time, the average temperature was ranged of 22.3 to 31.2 °C and pH ranges was 7.3 – 8.1. The Ipomoea aquatica (Chinese spinach) planted into HSFCW system and the growth parameters during the experimental operation observed. The Ipomoea aquatica growth parameters such as the plant height, a fresh and dry weights were monitored and measured. The influent and effluent of chemical oxygen demand (COD), ammonium nitrogen (NH4-N), total nitrogen (TN) and total phosphorus (TP) were examined. The removal efficiency for all parameters showed decreased with an increase in HLR from 0.15 to 0.333 m3/ (m2.day). The results demonstrated that the average removal efficiency of the COD, NH4-N, TN and TP during system operation is 52.9%, 64.6%, 58.2% and 72.8% respectively. These results confirm that the HSFCW has a good efficient in treatment and can be used for the nutrients and organic matter removal from the domestic wastewater.


2021 ◽  
Vol 25 (1) ◽  
pp. 640-649
Author(s):  
Linda Grinberga ◽  
Didzis Lauva ◽  
Ainis Lagzdins

Abstract Constructed wetlands as a treatment system are widely explored in different climate conditions and established to be effective in pollution removal from water environment. This study aims to demonstrate the performance of pilot-scale subsurface flow constructed wetland for storm water treatment in Latvia. The catchment basin was located in a farmyard of agricultural area and storm water was collected from the impermeable pavements. Storm water was accumulated in an open pond and periodically pumped above the filter part of the subsurface flow constructed wetland. Grab samples were collected once or twice per month at the inlet and outlet of the treatment system during a period of 73 months from year 2014 to 2020. Water quality parameters as nitrate nitrogen (NO3-N), ammonium nitrogen (NH4–N), total nitrogen (TN), orthophosphate phosphorus (PO4-P), and total phosphorus (TP), total suspended solids (TSS), biochemical oxygen demand (BOD5) and chemical oxygen demand (COD) were monitored. Water level at the inlet structure was automatically measured and flow rate was calculated based on the Manning equation for partially filled circular pipes. Results showed the reduction of average concentrations for all parameters during the study period. However, in some sampling cases concentrations increased at the outlet of the treatment system and can be explained by influencing factors of farming and maintenance. The treatment efficiency of NO3-N, NH4-N, TN, PO4-P, TP, TSS, BOD5 and COD concentrations was 17 %, 68 %, 55 %, 78 %, 80 %, 57 %, 80 % and 74 %, respectively. The study site demonstrated a potential to improve water quality in the long term.


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