Two controlled experiments were operated to evaluate the impact of pH on the treatment efficiency of azo dyes within artificial
textile wastewater using ponds as a polishing step. The objectives were to assess the (1) inflow water quality; (2) the
presence of Lemna minor and the algae Oedogonium spp. on the dye removal and the outflow water quality; and (3) suitability
of applying artificial textile wastewater and the impact of this wastewater and the dye on plants. Findings indicate that the
shallow ponds planted with L. minor and/or algae treated the dye Basic Red 46 (BR46) significantly (p < 0.05) higher than
the control ponds without any significant (p > 0.05) impact of pH. The potential of L. minor and algae for removal of BR46
was 31% and 25%, respectively. The removal of BR46 was around 89% for ponds planted with L. minor and algae, 58% for
algae ponds and 33% for control ponds. Wetlands with L. minor are successful and economic in the complete degradation
of BR46 at concentrations of 10 mg L−1 for any pH value between 6 and 9. The removal of ammonium-nitrogen (
NH4-N),
nitrate-nitrogen (
NO3-N) and ortho-phosphate-phosphorus (
PO4-P) was higher in planted than in unplanted ponds. The
mean outflow values of chemical oxygen demand, NH4-
N, NO3-
N, suspended solids and total dissolved solids were within
the limits for safe discharge. The artificial wastewater constituents after dilution (1 part of artificial wastewater to 24 parts
of raw water) were suitable to use within the treatment system containing L. minor.
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