Paper Information

Journal:   JOURNAL OF ENVIRONMENTAL SCIENCE AND TECHNOLOGY   FALL 2006 , Volume 8 , Number 3 (30); Page(s) 93 To 125.
 
Paper: 

THE CAPABILITY OF ANODONTA CYGNEA (UNIONIDAE) IN THE BIOLOGICAL TREATMENT OF URBAN WASTEWATER (AN OPEN SYSTEM APPROACH)

 
 
Author(s):  JAVANSHIR A., JANDAGHI M.
 
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Abstract: 

Agricultural and industrial sewages affect the quality of water everywhere and the dissolved phosphate and nitrate in such wastewaters create many environmental problems.
This study aims at reducing the dissolved components of wastewater using biological methods instead of the chemical ones. The swan mussel (Anodonta cygnea) is one of the most famous fresh water suspension feeders and seems to be an active agent for the removal of suspended particles and bacteria from water resources. To see whether A. cygnea is capable of reducing the nitrate and phosphate dissolved in urban wastewater, a number of them were placed in an open system at 19 - 20º C. Their filtration rate (ml. min-1. g -1 (Ash Free Dry Weight (AFDW)) and the retention rate of the dissolved phosphate and nitrate salts were measured. The volume of the water passed through the gills was calculated with the help of dixenic culture of Chlorella sp. and Scenedesmus sp. The algae developed in Guillard and Rhyter media and were used when their concentration reached about 400. 103 cells. ml-1. The results show that when fresh algae increase in number to meet their vital needs, they are capable of removing a considerable amount of the dissolved materials.  The dissolved nitrate tended to decrease from 204.17 mg.L-1 to 140.42 mg.L-1, and the filtration rate was about 10.01 ml.min-1.g-1 Ash Free Dry Weight (AFDW) during 20 minutes in the open system. Moreover, it turned out that there was a positive correlation between the weight and the specific filtration rates of mussels. While weight increased from 2.02 gr to 2.14 gr (AFDW), specific processed water also increased from 5.87 ml.min-1.g-1 AFDW to 10.01 ml.min-1.g-1 AFDW (p< 0.003). Furthermore, the results showed that an increase in the pollutants’ concentration resulted in an increase in the specific filtration rate by mussels. When nitrate increased artificially (by adding nitrate salts) from 84.53 mg.L-1 to 204.17 mg.L-1 in the inputs of the two experiments, the specific filtration rate increased from 5.87 ml.min-1.g-1 AFDW to 10.01 ml.min-1.g-1 AFDW and the nitrate concentration observed in the outputs from 66.97

 
Keyword(s): WASTEWATER TREATMENT, FILTRATION RATE, ANODONTA CYGNEA, PHOSPHATE AND NITRATE, CHLORELLA SP., SCENEDESMUS SP. ALGAE
 
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