Ultrashort Hydraulic Retention Time of Aeration and Nonaeration Constructed Wetlands for a Large Volume of Primary-Treated Wastewater from a Medical Rubber Glove Factory

Table 4

The average concentrations of pollutants in the wastewater after passing through the nonaeration HSFCWs system.

HRT/effluent recirculation	1st (2 hr.)		2nd (4 hr.)		3rd (6 hr.)		4th (8 hr.)
Parameters	Average	SD	Average	SD	Average	SD	Average	SD
pH	7.76	0.02	7.64	0.02	7.52	0.01	7.37	0.01
BOD (mg.l^–1)	2.04	0.02	2.56	0.01	3.12	0.05	3.88	0.24
COD (mg.l^–1)	65.00	5.77	55.00	5.77	37.50	5.00	25.00	5.77
FOG (mg.l^–1)	0.07	0.01	0.06	0.01	0.05	0.01	0.04	0.01
TKN (mg.l^–1)	0.02	0.00	0.03	0.01	0.03	0.01	0.03	0.01
TSS (mg.l^–1)	5.10	0.12	4.75	0.13	4.50	0.08	4.35	0.06
TDS (mg.l^–1)	166.00	3.65	147.50	5.51	135.00	2.58	132.00	5.16
EC (µS.cm^–1)	281.50	11.82	247.00	2.58	233.00	3.83	227.50	7.19
Salinity (ppt)	44.50	2.08	36.00	1.83	52.50	1.29	31.00	1.83
Temperature (°C)	30.45	0.06	30.45	0.06	30.45	0.06	29.63	0.01