Wastewater Treatment Plant for the City of Loja (Ecuador)

The wastewater treatment plant for the city of Loja meets the needs of the current population and enables comprehensive control of the problem of pollution and uncontrolled discharges into the River Zamora. Provisions have been made for the future expansion of the plant so that it can be extended in line with population growth. The WWTP implements technology that can be expanded without major increases in energy consumption, and the necessary spaces have been reserved onsite for the equipment required to augment the processes The treatment plant consists of two primary settling lines, two trickling filter lines and two secondary settling tanks. The treated water complies with the requirements for discharge into fresh water bodies set out in environmental legislation. The proposed design allows for the number of elements in each treatment operation to be increased in accordance with population estimates and quality parameters for the horizon year (+25).

DESCRIPTION OF THE WWTP

WATER LINE | INTAKE STRUCTURE AND LARGE-PARTICLE WELL

In the first phase of the project, the wastewater treatment plant for the city of Loja has a maximum inflow capacity of 5,208 m3/h and an average flow of 2,604 m3/h, giving it a current wastewater treatment capacity of 250,000 p.e.

The raw water is sent to the WWTP by means of a glass fibre reinforced polyester (GRP) sewer pipeline with a diameter of 1,400 mm.

The large particle well has a volume of 79.1 m3 and is equipped with a 250 I. clamshell grab to remove bulkier waste. The well is fitted with a manual bar screen with a passage size of 100 mm to protect the large particle filters. Maintenance of the clamshell grab is carried out with the aid of a 1,250 kg electric hoist.

The large particle well is fitted with a safety outlet pipe of 1,400 mm in diameter, connected to the general plant bypass line.
The large particle well receives the discharges from primary and secondary settling, as well as the discharges and supernatants from the grit classifier and grease separator, which are sent to the well by means of 2 (1+1 standby) submersible pumps, each with a capacity of 170 m3/h.

WATER LINE | PRETREATMENT

The rough filtering unit consists of four channels of 1.1 m in width, which are equipped with automatic upstream and downstream sluice gates.

Three of the channels are equipped with automatic bar screenS with a 20 mm passage size and have a maximum capacity of 1,823 m3/h, while the fourth line is fitted with a 10 mm manual bar screen for emergencies.
Three automatic fine screens with a 5 mm passage size are installed downstream of the bar screens.

Published in: #83 FuturENVIRO September – October 2021