Rural Domestic Wastewater Treatment by Small-scale Horizontal Subsurface Flow Constructed Wetlands at Different Temperatures

Abstract

This study assessed the performance of a small-scale horizontal sub-surface flow constructed wetland (HSSF-CWs) for rural domestic wastewater treatment with different species of vegetative plants capsicum annuum (A), Allium sativum (B), Apium graveolens (C), Spinacia oleracea (X), Apium graveolens (Y) & cilantro (Z).The system operational time was over three months as a tertiary treatment for both summer and winter season to improve the effluent quality before disposal. The average temperatures during the experimental operation were 27°C and 11.6°C in summer and winter respectively. The average pH value ranges between 6.98-7.19 and 6.72-6.98 respectively. The average hydraulic residence time (HRT) of 2 and three days with the hydraulic loading rate (HLR) set to 180ml/min in summer and winter respectively. The average removal efficiency (RE) concentrations for plants A, B & C in summer were 77.2%, 77.2%, 81.4% & 93% for TN, NO3-N, NH4+N & TP. Whereas in the winter season the RE were 67.6%, 65%, 69.4% & 86.6% for TN, NO3-N, NH4+N & TP for plants X,Y,& Z respectively. All the vegetative plants almost performed similarly in nutrient removal under HRT of two and three days with the best performance revealed in summer. HSSF-CW successfully achieved high removal efficiency due to its self-adaptability, low-cost, secure operations and maintenance and above all is high effluent quality reuses and self-remediation. HSSF-CW is a good alternative for wastewater treatment system.