Gurney Environmental continuing their work with SAGUAPAC in Santa Cruz, Boliva
Gurney Environmental has continued to work on the installation of an internationally tendered, World Bank funded project to address wastewater processing issues in the city of Santa Cruz, Bolivia.
The 1.8 million population city's infrastructure is being put under stress due to significant population growth. The wastewater treatment plants (wwtp) have been in an overloaded condition resulting in low rates of processing, sludge accumulation and odour issues.
The operations company, SAGUAPAC, has four wwtps located in various parts of the city. The North wwtp utilises facultative cells of about 50 hectares in area and receives a flow of 30,000 m3/day and a BOD load of 3,900 kg/day. The design load on the primary cells exceeds prudent design standards by about 6 times, thereby resulting in a complete lack of dissolved oxygen (DO) in the water column with consequential odour and processing problems.
Normally SAGUAPAC would have constructed more cells to increase treatment capacity but as no land was available at this wwtp, being hemmed in on all sides by the city's encroachment, another option was needed. In similar situations, in other parts of the world, a more mechanised method of wastewater treatment, such as activated sludge for instance, might have been chosen, but this was not deemed cost effective or sustainable.
Instead a Gurney Environmental Accel-o-Fac® design and equipment upgrade was installed.. Within 6 weeks of commissioning the cells established a DO content - the first time this had happened. The odour had dissipated and the processing rates and treatment performance increased significantly. The lagoons continued to operate at pre installation flows and loadings and maintained a good DO level throughout with a healthy green colour as would be expected.
In order to be able to keep up with the increasing wastewater flows SAGUAPAC, have gradually increased the wastewater loading on the primary cells up to about 1.7 times pre installation levels, at which point the lagoons started to lose their colour and the DO levels dropped off, albeit no odour resulted. SAGUAPAC has since reduced the loading to about 1.5 times pre installation levels and has elected to operate the lagoons under these conditions ever since.
The Accel-o-Fac® system has provided an overall improvement in lagoon treatment capacity enabling a 50% increase in flow throughput with only a modest expense in equipment and a negligible increase in operating costs. Compared with alternatives Accel-o-Fac® offered best value for money and, through use of the abundant winds, the most sustainable upgrade option.
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