Remoção de matéria orgânica e fosfato de esgoto de restaurante universitário via wetland de fluxo vertical em fase de start up

Abstract

The aim of this work was to evaluate the efficiency of a vertical subsurface flow constructed wetland system with partially submerged bed planted with Heliconia rostrate in the treatment of sewage generated in a university restaurant. The experiment was conducted over 38 days with 0,25 m of bed saturation. The constructed wetland system was fed with sewage of the university restaurant of the UTFPR Campus Londrina in pulses, twice a day (1:00 pm and 1:00 am), each pulse providing 25 liters of sewage into the system. Samples of raw sewage and treated effluent was collected twice weekly and subjected to physicochemical analyses, COD, phosphate, alkalinity, pH, total solids and total suspended solids. For the composition of the filtration media, have been used gravel (class 0, 1, 2) and medium sand (d10 = 0.1877 mm, d60 = 0.3628 mm, U = 1.9329). Based on the results of the first 38 days of system operation, it’s possible to conclude that: hydrographs showed that the hydraulic detention time of the system at the beginning stood in around 90 minutes, evolving to 160 minutes after one month of operation. The average loads applied to the system were: 33,24 g day-1 COD, 34,89 g day-1 of TS, 8,22 g day-1 pf TSS and 0,34 g day-1 of phosphate. During the startup of the system, average values for the raw sewage were 664.80 mg L-1 COD, 6.99 mg L-1 P-PO43-, 112.60 mg L-1 CaCO3, pH 6.94 and 164.41 mg L-1 TSS. After the system operation, global average efficiencies were obtained from 97.02% COD removal 89.15% P-PO43-, 92.90% TSS. Were observed low total solids removal, due to the inability of the constructed wetland to remove dissolved solids. The plants employed in the process had difficulties to adapt in the first few weeks, requiring the replacement of 2 plants. The vertical flow wetland system with partially submerged bed showed high rates of nutrients removal, attending the parameters for releasing effluents into water bodies, required by law, reinforcing the possibility to be used as a treatment system in places without access to sewage collecting system.