Water is a colorless and odorless liquid that support the existence of life for all living things. It enhances digestion processes and improves metabolism. To about 70% of human body is occupied by water. Despite of improving health effects of living things, water enhance the attainment of sustainable development since it make the society to improve their economical, social, political and financial status through performing various activities that depend to the availability of water including agriculture, fishing, transportation, recreation, security, and alike. The quantity of water in the world is constant and is enough to all organisms but its distribution is unevenly due to a number factors such as the variation in climatic condition, the extent of see breeze and land breeze to change evaporation rate, the impaired quality for the intended use as well as the location of the organisms seeking to have water. The access to safe, clear and reliable water is the indispensable need and right for every human being and this water should meet the quality as described in drinking water quality standard of 2002 described by world health organization, Environmental Standards Compendium (Water Quality Part I – III) prepared by the International Organization for Standardization (ISO) in 1994 as well as national Environmental Standards Compendium (TZS 789) established by Tanzania Bureau of Standards in 2003 that it should be free from microbes like fecal and total bacteria, heavy metal contamination, less turbid, and recommended concentrations of physico-chemical parameters.
As described in National Water Policy to fulfill its objectives; the access of quality water services is a right of every Tanzanian. Hence Chalinze water supply and sanitation authority is striking the balance between the social principles of the Right to Access Safe and Clean Water and the objective of Optimum Revenue collection by ensuring that all Consumers within an area have access to Quality Water Services at Reasonable and Affordable costs, and disengagement shall be carried out as a last remedy after all means to collect the debt have botched. Those who are unable to have house connections shall be provided with alternative means to access Safe and Clean Water, including water Kiosks and Public Tapes services.
Chalinze Water Supply and Sanitation Authority was established on 2012 from formally known Chalinze water supply project that established in 2003 and it uses water from Wami River as viable source. The River was discovered in 1906 and lies entirely within Tanzania between 6o7` South and 38o49` East to 6o117` South and 38o17` East in Coast region and Morogoro region in eastern Tanzania with square kilometers of 43, 964. Its source is specified in the Kaguru Mountains and it flows east entering the Indian ocean with discharge of 60.6m3/second. But its catchments area extend from Kinyasungwe River to far beyond Dodoma to the Southern edge of Maasai Steppe where in course of flow there are Mkondoa, Kitanange, Kisangata, Tame, Mkundi and Mtibwa Rivers. The name Wami originated only after leaving Mkata River basing on the northern edge of Mikumi.
Due to the high pollution of the river especially during rain seasons, the authority have water treatment plant that contains four units comprising of intake, clarification and sedimentation, filtration, as well as storage and two chambers which are coagulation and disinfection.
The purpose of the intake is to suck and pump raw water to clarifiers via coagulation chamber. The unit contains four vacuum pumps number from 1 to 4 such that 1 and 2 are rated to power of 11kw and have pumping capacity of 100m3/hour each while 3 and 4 are rated to a power of 18.5kw and have pumping capacity of 200m3/hour each. Because the treatment plant misses water screening unit, the inlet pipes are designed with the micro screening membrane to the mouth of each and the area is marked by scaffolds.
At this chamber, the coagulant is mixed with raw water for coagulation process. The mixture is directed to clarification unit. The most coagulant used is alum as metal salt and in failure to zeta potential to van der waals force of the suspended and colloidal particles, algae Floc as Bentonite is used to gather to provide the coagulation aid. The concentration of metal salt is almost of 10% and the concentration of Bentonite is determined by jar test experiment depending to the turbidity and hydrogen concentration content of raw water but does not exceed 92mg/L. the dosing of the coagulant is by centrifugal pumps with the set dose determined by jar test practice depending on the turbidity and hydrogen concentration content. The processes of preparing the stock solution and performing dosing of the coagulant are done in the special room called dosing room. The system is electrified and is within the enclosed route. Two meters are commonly used to determine the clarity and taste of water before and after treatment. These meters are of turbidity and pH. If after test the clear water observed to have pH below to the recommended standards the additional of sodium bicarbonate as lime is done after performing another jar test for its concentration and dose.
Clarification & Sedimantation
The authority currently has two clarifiers with maximum capacity of 200m3 each. The purpose of clarification and sedimentation unit is to provide both detention and retention times for raw water with coagulant to destabilize the particles associated with turbidity. The detention time is determined by intake pump setting which can be 4hours, 2huors and 1.3hours. The retention tine depends on the determination of optimum dose of coagulant and turbidity content of raw water. After destabilization; the particles settle down the bottom of the clarifiers by gravity where will be removed as sludge by performing big wash or small wash processes. The frequency of big wash depends to the reduced aesthetic value of raw water and the amount coagulant dose applied.