Phytoremediation Study and Effect of pH on Biomass Productivity of Eichhornia crassipes - Management of Natural Resources in a Changing Environment - page 193

01-Apr-12
20-Apr-12

350

300

250

200

150

100

50

0

C-1
(pH=7.6)

T-1
(pH=5)

T-2
(pH=6)

T-3
(pH=7)

T-4
(pH=8)

T-5
(pH=9)

Control & treated cultures:

Fig. 6 Initial and fi nal day total-nitrogen values of Hindon rive wastewater at different pH

Ammonia is toxic to aquatic life and toxicity is affected by pond pH. Ammoniacal-
Nitrogen (NH 3 -N) has an extensively high toxic form at high pH and a less toxic
form at low pH. In addition, ammonia toxicity increases as temperature rises (Wurts
2003 ). The value of total-nitrogen in Hindon river wastewater was found to be
292.06 mg/l on initial day of culture study. The present investigation shows that the
maximum reduction in total- nitrogen value was found in T-1 (pH = 5) [78.41 %]
while minimum reduction was found in T-3 (pH = 7) [62.15 %] during 20 days
course of culture study (Fig. 6 ).
As per our main objective of the present investigation, the effect of pH, in six
different combinations was investigated (Table 3 ). All the data on biomass produc-
tion at different pH were varying considerably. Maximum production of net bio-
mass was recorded in T-3 as 197.60 ± 0.14 g, while minimum biomass production
was recorded in T-1 as 87.49 ± 0.95 g on fi nal day of wastewater culture study
(Fig. 7 ). The maximum increase in biomass production at pH = 7 and pH = 8 may be
due to increase in the nutrient uptake and immobilization capacity of Eichhornia
crassipes at neutral and slightly alkaline pH.

Conclusion

According to Delgado et al. ( 1994 ), with an increase in pH, the ionic forms of the
micronutrient cations change to hydroxides or oxides. This indicates that the
Eichhornia crassipes has a tendency to neutralize an aquatic environment. Therefore,
it is necessary to add a base or an acid in order to maintain the required pH range as
outlined by Delgado et al. ( 1994 ). Minor fl uctuations were observed in the pH val-
ues of treatment cultures; therefore periodic maintenance of pH was carried out
after every 24 h.