DESIGN, CONSTRUCTION, AND PERFORMANCE TEST OF WASTEWATER SLUDGE FILTER IN THE TOLON DISTRICT OF THE NORTHERN REGION OF GHANA

Wastewater sludge has garnered global interest since its generation in terms of source, volume, quality, treatment, disposal, or reuse. It has an impact on human life and other natural resources, most notably fragile ecosystems. The study was carried out at the Savannah Research Institute (SARI) in the Tolon District of the Northern Region of Ghana. The main objective was to design, construct and test the performance of a filter for the treatment of wastewater sludge for irrigation. The filter design consisted of two poly tanks, with one labeled as a sedimentation tank and the other one as a filtration tank. Both tanks' specifications were; the flow rate of the sedimentation tank was 0.18 L/s, the height of the tank was 1.52 m, the diameter was 1.23 m, the surface area of the tank was 0.19 m2 and the volume was 1.81 m3. The sedimentation tank was installed to accommodate the wastewater sludge for pretreatment. HDPE pipe of 100 m was connected to a 35 m3/h gasoline pump to lift the wastewater sludge from a 100 m distance from the source to the sedimentation tank. The filtration tank was filled with local geologic materials such as crushed stones, chipping stones, and river sand. Each layer had a height of 0.4 m and the total bed height was 1.2 m. The order of the arrangement of roughing filter materials was crushed stones as the first layer at the bottom of the tank with sizes ranging from 18-24 mm, chippings at the second layer with sizes of 8-12 mm, and the third layer river sand with sizes of 4-8 mm. The filtration velocity and up-flow velocity were 1.5 m/h. The most porous material among the three (3) filter materials used are crushed stones, which had a porosity of 44.7 %. However, river sand was almost non-porous, recording a value of 5.9 %. After the wastewater sludge from the sedimentation tanks which contain alumium salts, suspended solids and sediments had been filtered with the constructed roughing filter, desirable levels of physical, chemical, nutrient, and microbiological parameters were obtained, and they were within the acceptable limits of FAO or WHO, or EPA. The pH level moved from 6.20 before filtration to 6.61 after filtration; from 102.67 to 0 mg/L after filtration for TDS, and 8198.67 to 19.0 NTU after treatment for turbidity. The salinity level dropped significantly from 201 to 0.002 mg/L representing 99.99 % removal efficiency. Dissolved oxygen (DO) also improved as well as the other parameters. The total coliform, faecal coliform, and E.coli count reduced drastically from 200 to 100 cfu/100 ml, 60 to 8 cfu/100 ml, and 25 to 4 cfu/100 ml respectively. It is recommended that the filtered and unfiltered wastewater sludge generated at SARI water treatment plants can be used to irrigate various kinds of vegetables to monitor the impact of the filtered and unfiltered wastewater sludge on the growth and yield of these vegetables. Also, there is a need to establish infrastructure and rehabilitation of broken structures at already existing plants to accommodate wastewater sludge at water treatment plants across the country to further treat this wastewater for irrigation purposes especially in water-scarce areas to help feed the ever-growing population.