Abstract:
The use of aquatic macrophytes for the domestic wastewater treatment is increasing in various parts of the world. The aim of this
study is to examine the potential of shallow pond system using water hyacinth (Echhornia crassipes) along with the
microorganisms present in the bio-film attached to the roots and water column for treatment of domestic wastewater in the
presence of high total dissolved solids (TDS) and heavy metal salts. The shallow pond system is different from conventional water
hyacinth system and it has high oxygen rich zone to provide the superior growth of aerobic microorganism. The studies indicate
that, water hyacinth can tolerate TDS up to 2000 mg/L in the shallow pond system. The heavy metal removal is a function of
phytoaccumulation or phytoextraction, which can lead to morphological deformity if heavy metals exceed the saturation limit of
268 & 2152 mg/kg Cd, 381 & 3372 mg/kg Cu, 229 & 1850 mg/kg Ni, 462 & 2764 mg/kg Zn, in shoots and roots respectively.
The reduction in TDS is marginal (19%) at the highest tolerable limit whereas the heavy metal reduction is 66%, 68%, 64%, 70%
for Cd, Cu, Ni and Zn respectively at the outlet of the treatment system. The sewage treatment performance of the shallow pond
water hyacinth system for all other parameters is estimated as 81% Chemical oxygen demand (COD), 91% Biochemical oxygen
demand (BOD5), 16% Total dissolved solids (TDS), 70% Total suspended solids (TSS), 4% Chlorides, 74% Ammonia nitrogen
(NH3-N), 41% Phosphate (PO4-P), 96% Most probable number (MPN) and 98% Total viable count (TVC) reduction.

Alireza Valipour, Venkatraman Kalyan Raman, Parastoo Motallebi