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B. Niroula / Our Nature (2003) 1: 10-14

Materials and Methods Wastewaters from the Sub-metropolitan Sewage of Biratnagar and following industries

were selected for the study.

  • Diesel Power House

electricity)

(producing

Hetaunda Iron & Steel (manufacturing

iron rods construction)

for

building

&

road

  • Hulas Wire (manufacturing galvanized iron products)

  • Himalaya Soap & Chemicals (producing different types of soaps).

  • Leather Industry.

  • Shah Udyog (Textile Industry)

The industrial effluents were collected in polythene containers directly from the outlet of the factories while sub metropolitan Sewage was collected from the discharge point of sewer located at the bank of Singhia River. Colour (visual appearance), pH, dissolved oxygen (Winkler's method) and solute particles (Zobel et al.1987) were recorded immediately after sample collection. The collected wastewaters were stored in dark at room conditions for future uses.

Germination experiments were carried out in petridishes (dia 9 cm) in triplicates under room conditions. Two third portion of each petridish was filled with sand soaked in undiluted effluent/ Sewage and each petridish contained 25 seeds. Control experiment, which was performed with tap water. Seven and four days old seedlings from rice and blackgram petridish respectively were taken randomly and their respective longest root and shoot lengths were measured for each treatment and control. Data of seedlings were analyzed statistically using student's t test.

Results and Discussion Himalaya Soap and Chemicals had the highest amount of dissolved solutes (145.1g/1), lowest dissolved oxygen (0.9 mg/l) and alkaline pH (11) range in comparison to other industrial ef luents and Sub metropolitan sewage (Table 1). Hulas Wire ef luent had acidic pH (4) and the values ranges 6 to 8 in other industrial ef luents and Sub metropolitan sewage. Similarly dissolved oxygen and dissolved solutes ranges 0.83 mg/l to 1.8 mg/l and 0.2 g/l to 3.7 g/l respectively while the values were 3.2 mg/l and 0.1 g/l for tap water.

Ef luent of Himalaya Soap & Chemicals inhibited germination completely for both the tested seeds. In rice, germination is greatly inhibited by the ef luent of Leather Industry and limited to only 5% but it stimulates the blackgram. (Table 2). Ef luents of Diesel Power House had considerable inhibitory effects but

ef luent of Hetaunda Iron & Steel, Hulas

Wire

and Shah Udyog had negligible

inhibitory

effect

on

germination.

Sub-

metropolitan

sewage

promoted

germination

slightly in chemicals,

rice. other

Except Himalaya Soap industrial ef luents had

and no

considerable

negative

effect

on

seed

germination

of blackgram. Indeed, the ef luents Iron & Steel, Leather Industry and had promontory on blackgram.

of Hetaunda Shah Udyog

In seedling growth of blackgram, root growth is not signi icantly affected by all the tested Industrial ef luents and Sub-metropolitan Sewage (Table 3). Shoot growth is signi icantly inhibited by the ef luents of Diesel Power House (Hypocotyl F= p 0.01, Epicotyl F= p 0.05). Shah Udyog (F=p 0.01) and Hulas Wire (F= p 0.05) ef luents inhibited the hypocotyl growth signi icantly. Other ef luents/sewage had no signi icant effect on growth of shoot (hypocotyl + epicotyl) in blackgram. Whole seedling growth of rice (root + shoot) is signi icantly affected by the ef luents of Leather Industry (F=P 0.01).

11

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