Environmental Engineering Reference
investigation, the physicochemical analysis of wastewater was conducted on initial
day and after 20 days of wastewater culture study. The details of physicochemical
analysis of wastewater has been recorded in Tables 1 and 2 .
The main objective of our study is to fi nd out the best possible pH range for
maximum Eichhornia biomass production. According to Haller and Sutton ( 1973 ),
maximum growth of Eichhornia crassipes occurred in acid (pH 4.0) to slightly alka-
line (pH 8.0) pH range. Therefore, it was decided to carry out the biomass produc-
tion under variable pH range.
Temperature is one of the most important factors in an aquatic environment. In
fact, no other single factor has so many profound infl uences and direct and indirect
effects (Welch 1952 ). A close correlation between air and surface water temperature
has also been reported by Mc Combie ( 1959 ) in one of his studies as has been noted
in the present study also.
The mean air temperature fl uctuated from 18.5 °C to 32.1 °C throughout the
course of study. The mean air temperature at study site was recorded at 22.75 °C,
25.2 °C and 26.85 °C on initial, 10th and 20th days of wastewater culture study
respectively. The surface water temperature followed a trend similar to that of air
temperature. Mean water temperature fl uctuated from 15.4 °C to 28.3 °C through-
out the course of study. The mean water temperature at study site was recorded at
19.3 °C, 21.55 °C and 22.6 °C on initial, 10th and 20th days of culture study
The DO value 5.0 mg/l is the standard for drinking water (Bhanja and Patra
2000 ). The value of DO of Hindon river wastewater on initial day of culture study
was recorded as 2.5 mg/l. The condition of DO is complex with respect to other
parameters. The maximum mean value of DO was recorded as 5.8 mg/l while the
minimum value was registered as 1.9 mg/l in T-4 (pH = 8) and T-1 (pH = 5) cultures
respectively on 20th (fi nal) day of study (Fig. 1 ).
Biochemical Oxygen Demand (BOD) is used to determine the relative oxygen
requirements of wastewaters, effl uents and polluted waters (APHA 1999 ). Maximum
reduction in BOD was shown by treatment culture T-3 (pH = 7) [83.1 %] followed by
treatment culture T-4 [81.3 %] during 20 days of wastewater culture study (Fig. 2 ).
The COD determines the chemical oxidisable organic matter present in water
(Kolhatkar et al. 2012 ). The extent of sample oxidation in COD test can be affected
by digestion time, reagent strength and sample COD concentration (APHA 1999 ).
The COD value of Hindon river wastewater was found to be 184 mg/l on the initial
day of culture study. The present investigation shows that the maximum reduction
in COD value was found in T-3 (pH = 7) [69.7 %] while minimum reduction was
found in T-5 (pH=9) [67.1 %] during the 20 days course of wastewater culture
study (Fig. 3 ).
Ansar and Khad ( 2005 ) reported that intolerable levels of phosphates and nitrates
to local organisms have been known to deplete dissolved oxygen levels by causing
algal blooms. The concentration of phosphate in wastewater was found desirable on
initial day of culture study. The concentration of phosphate was consistently
decreased in all the treatments. However the highest reduction rate was found in T-4