Limnology

• Study area
  • Name: Adi-Ganga Canal
  • Others Name: Gobindapur Creek, Surman’s Canal, Tolly’s Canal
  • Length: 75 Km

• Introduction

Adi-Ganga canal, an important navigational canal is the main channel of Bhagirathi-Hoogli River flows through the center of south Kolkata. It was the main flow of the Hoogli River from 15^th to 17^th century but now at some places it is totally dried up.

• Historical significance:

Nawab Alivardi Khan (1739 – 1756) hired Dutch engineers and excavated the canal. During 1775 -1777, a British service-man of East-India Company named Major William Tolly excavated this canal to engage import and export via Adi-Ganga.

• Water Source: Bhagirathi-Hoogli river, rain water.
• Location : Kolkata, West Bengal

• General water quality
• Chemical properties (in past five years)
• Range of Biological Oxygen Demand

Highest: 43.54 mg/L, The lowest: 2.94 mg/L (In past five years)

• Range of DO

Almost zero, Highest: 4 mg/L, Lowest: 0.5 mg/L

• Fecal Coliform

Ranges between 10 lakhs to 70 lakhs

• pH

Varies between 7 to 8.5

• Water Temperature

Varies between 20° C to 35°C

• Total Coliform

Ranges between 20 lakhs to 90 lakhs

• Chemical oxygen demand

Highest: 208.00 m/L , Lowest: 6.00 mg/L

• Total suspended solids

Parameters	Range	Permissible
Lead	0.01-0.02 ppm	0.1 ppm
Nickel	0.22-0.36 ppm	–
Zinc	0.0046-0.0104 ppm	5.0 pmm
Cadmium	0.005-0.01 ppm	0.01 ppm
chromium	0.023-0.050 ppm	0.05 ppm
Arsenic	BDL	0.01 ppm

• Physical properties
• Color: Blackish, Dark brown or Mod ash
• Adour: septic, rotten eggs or fishy
• Visible effluent discharge: Moderate to high with floating algae.

Present Scenario

• Scientific solution

What should we stop?

•  Adi-Ganga contains high coliforms, BOD & suspended solids.
• So firstly, we should avoid releasing construction waste and the untreated sewage in to lakes.
• Avoid throwing solid waste, plastic, things made up with metals.
• Avoid harmful untreated chemicals, hot water and ass released from industries.

What we should do?

Artificial Aeration

Process	Advantages	Disadvantages
Air flow into water	Improves water quality, easy to apply, sustainable	Costly, maintenance requirs

Water Transfer

Process	Advantages	Disadvantages
Clean water will be mixed with polluted water	Promote self purification system	Costly and labour intensive

Mechanical Algae Removal

Process	Advantages	Disadvantages
Removal of algae by mechanical process/netting	Improve water quality	Costly during operation

Biological Treatment

The microbes eat up contaminates such as oil and organic matter. Letting off carbon dioxide and water.

Water Treatment by Using Floating Beds

• Plant base floating bed
• Ecological floating bed
• Floating Wetland/artificial floating islands
• Combine floating bed
• Hydroponic floating bed
• Hybrid floating bed
• Multistage floating bed
• Enhanced floating bed
• Aqua mats
• Endophyte floating bed
• Stereo floating bed

Chemical Treatment

Process	Advantages	Disadvantages
Flocculation, Precipitation, Oxidation, Algaecides	Quick remediation	Temporary, produce secondary waste

Remediation by Aquatic Animal

• Gastropods: Bio indicator of heavy-metals
• Silver carps, common carps, snail: reduce concentration of nutrients, eutrophication.
• Conclusion

Adi-ganga carries all the drainage water and sewage of south Kolkata. Therefore sewage and waste treatment is required.

• References
• A comparative study of Microbial status and Dissolved Heavy Metals in River Ganga and Adi Ganga (Tolly’s Nullah), Kolkata, India,  A.Bhattacharjee & Dr. S.Bose
• Remediation of Polluted River Water by Biological, Chemical, Ecological and Engineering Processes, Hossain Md Anawar 1,2 and Rezaul Chowdhury 3,*
• West Bengal pollution control; water quality parameters
•  https://images.app.goo.gl/SjB4N66sW6qNBqSg7
•  https://images.app.goo.gl/v73pN4MJEKtK7vF58
• https://images.app.goo.gl/D47GBmZNhJn9iXns9