Water Science & Technology Vol 19 No 8 pp 107–119 © IWA Publishing 1987

Comparison between a Perforated Pipe and a Fixed Sprinkler System for Land Disposal of Treated Petrochemical Effluent

Zeno Simon^*, Mario L. Baldasso^*, Adejalmo F. Gazen^** and Juan C. Aguirre^**

At SITEL — the integrated effluent treatment system of Pólo Petroquímico do Sul (South Petrochemical Complex, Triunfo, Brazil) — the tertiary-treated effluent is disposed of on land at an average hydraulic application rate of 140 m³/ha.day. Two subsystems have been installed in order to minimize the devastation of indigenous vegetation during the construction phase, aiming also at investigating the cheaper processes to be adopted when expansions become necessary.

The first subsystem consists of a network of perforated PVC pipes which distribute the effluent over a forested area through an arrangement compatible with the local basin divides. It is fed by six submersible centrifugal pumps operating at moderate heads (ca. 30 m H₂O). The second subsystem comprises high capacity rotating impact sprinklers fixed on hilltops covered predominantly by grasses. It is fed by two dry well centrifugal pumps operating at higher heads. The design criteria for both systems stem from a “zero runoff” legal requirement applicable within the limits of the 100 ha disposal site.

The two subsystems are compared as regards technical aspects and economics. Removal efficiencies are presented. Capital and running costs related to pumping stations, mains, distribution networks, ancillary equipment and appurtenances, power consumption, maintenance, operation, materials etc. are compared and discussed. Functions and indexes that may prove useful in feasibility studies for similar systems are presented.

Keywords: Land disposal, effluent irrigation, grass filtration, sprinklers, perforated pipes, pumping stations, economics of land disposal, cast iron mains.

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