1. FACTORS AFFECTING THE SCUM FORMATION:
A CASE STUDY OF ETHEKWINI MUNICIPALITY (SOUTH AFRICA)
Surabhi Srivastava, Susan Mercer , CristinaTrois and Chris A Buckley
University of KwaZulu-Natal
Tuesday, 29 Nov. 2016
Howard College Campus
INTRODUCTION
From 2005 the EThekwini Water and Sanitation (EWS) in Durban has been facing excessive scum accumulation in its wastewater installations. The table1 provides information from the other countries on the sewer overflows caused by the scum. The table 2 shows internal and external and factors affecting scum formation. Limited information on the factors affecting the scum formation.
Country
Overflows(%)
Reference
USA 47
Keener et al. (2008)
England 50
Williams et al. (2012)
Australia 21
Silva et al. (2011)
Sweden 35
Mattsson et al. (2014)
Norway 25
Malaysia 70
Husain et.al (2014)
South Africa NR
Mahlobo (2008)
Factors affecting the scum formation
Internal
External
Soaps, fats, oils and grease
Metal Ions
Location
Water supply
Anaerobic digestion
Weather
Socioeconomic – income , food culture and lifestyle
Table 1
Table 2
METHODOLOGY
232 wastewater pump stations in eThekwini Municipality.
Central beach pump station was selected to monitor the scum deposition as the excess scum and overflow would effect tourism .Fig1 green dot is location of pump station , small dots are food establishments and blue dot is rain gauge .
The scum depth was monitored every week Fig 2 shows the measuring procedure and the scum accumulation on wall.
The data on rainfall weekly was taken from the nearest rain gauge.
Fig.2
Fig.1
RESULT
DISCUSSION
From the graph we discuss about relation between the rainfall and the scum formation.
In first week 30 mm of scum was deposited after clean up with no rainfall .
The week 2 had scum growth of 10.5 cm with weekly rainfall of 11.9 mm.
Week 3,4 and 5 had heavy rainfall which resulted in small amount of deposition.
Week 6 and 7 the deposition again started with average rainfall of the two weeks mm.
A heavy rainfall of 40mm was observed in 8th week which
damaged the scum deposition.
However, the linear line in the graph indicates overall increase in the scum formation. The scum formation on the central beach pump station is affected by rainfall.
CONCLUSION
The scum formation and deposition on wall in central beach wastewater pumping station is affected by the rainfall , food establishments and hotels. Combination of various factors affect the scum deposition.
The scum damages the parts of wastewater installations and the operation, maintenance and repair are expensive.
It is necessary to safeguard and prevent the scum formation to avoid sanitary sewer overflows and other damages in sewer lines.
Our eating habits and lifestyle is not only affecting our body but also affecting sewer system of the city.
FUTUREWORKS
More data is required for the scum quantification for the management on the landfill sites.
More experimental analysis is required for converting scum into biodiesel as renewable energy resource.
ACKNOWLEDGMENT-We are thankful to eThekwini municipality water and sanitation unit for funding this project. Special regards to EWS staff Mr Roshen Mohanlal (Pump-station superintendent) and Mr Pele (SPO) .