(602az) Integrated Use of Geographic Informational System and MIXED-Integer Linear Programming for Indentifying Optimal Agricultural Areas for Sewage Sludge Amendment: A Case Study of Catalonia

INTEGRATED USE OF GEOGRAPHIC
INFORMATIONAL SYSTEM AND MIXED-INTEGER LINEAR PROGRAMMING FOR INDENTIFYING
OPTIMAL AGRICULTURAL AREAS FOR SEWAGE SLUDGE AMENDMENT: A CASE STUDY OF
CATALONIA

P. Vaskan[1], A.
Passuello[2], G.
Guillén-Gosálbez[3], M.
Schuhmacher[4], L.
Jiménez[5]

Departament d'Enginyeria
Química (EQ), Escola Tècnica Superior d'Enginyeria Química (ETSEQ), Universitat Rovira i Virgili
(URV), Campus Sescelades, Avinguda
Països Catalans, 26, 43007 Tarragona, Spain

Abstract

Deciding the best agricultural soils for sewage sludge amendment
is not a trivial task. Several environmental aspects, such as groundwater
contamination by nitrates, open waters and soil protection, as well as human exposure
to the contaminants present in the sludge matrix must be considered along with
economic aspects, making this task quite challenging. This is because the
management of this residue concerns different stakeholders, with different
views of the problem and conflicting interests. In addition, they may find that
their interests are not reached, fact that leads to a low acceptance of the
practice.

Reaching a final solution satisfying all the decision-makers
involved is indeed very challenging. Systematic tools
based on multi-objective mathematical programming are well suited to tackle
this type of problems, as they allow generating and assessing a large number of
potential solutions. The final goal is to calculate a set of Pareto optimal
alternatives, that is, a set of solutions with the property that it is
impossible to improve them in one of the objectives without necessarily
worsening at least another criterion.

In this work, we study the use of multi-objective optimization
for identifying the best geographical areas for sewage sludge (SS) amendment in
terms of economic and environmental criteria. Our approach integrates
geographic informational systems (GIS) and multi-objective mixed-integer linear
programming (MILP) within a unified framework that allows exploring in a
rigorous and systematic manner a large number of alternatives for sewage sludge
amendment from which the best ones (according to the decision-makers'
preferences) are finally identified.

The capabilities of our approach were tested through its
application to a case study based on Catalonia.
Given a certain amount of sludge to be treated and a set of
available agricultural areas. Numerical results show that it is possible
to improve the environmental performance of the final solution by compromising
the associated cost. Our methodology is intended to assist decision-makers in
such a challenging task.