IMPACT OF ELEVATED TURBIDITY AT KATHITA RIVER IN MERU COUNTY ON QUALITY OF TREATED WATER AND COST OF WATER TREATMENT

ABSTRACT

The purpose of this study was to investigate the impact of the elevated turbidity in Kathita River

on the quality of treated water and cost of water treatment. Turbidity of raw water from Kathita

River varies greatly during the study period, reaching highs of over 264.0 NTU. Turbidity data

was obtained from Meru Water & Sewerage Services (MEWASS) for 2013 and 2014.

Confirmatory laboratory tests were carried out on water from Thika River.

Despite variation in raw water turbidity, treated water turbidity remained well below the

statutory value of 5.0 NTU. Confirmatory tests showed that both alkalinity and pH of treated

water are inversely proportional to the amount of coagulant added.

Cost analysis indicated that the cost of alum is directly proportional to the level of turbidity in

Kathita River. The average alum dosage was 37.52 mg/l which translated to an average daily

cost of alum of Kshs. 11,256.50 per 4,150 m3/d of production. An increase of 10 NTU in

turbidity would result in a cost increase of more than Kshs. 1,600 per day which is equivalent to

14.2% of the average daily cost. Consequently, the study concluded that there is need for

measures to improve the quality of river water sources so as to reduce the cost of water

treatment.

 

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