Self-Organizing Porous Media in Environmental Engineering: A Review of Attenuation, Stabilization and Control Pathways

Environmental porous media are widely used to convey, attenuate, transform or contain pollutants in landfills,
drainage layers, permeable reactive barriers, biocovers, biofilters and contaminated aquifers. They are still often
designed or assessed through initial material properties such as porosity, hydraulic conductivity, sorption capacity,
batch leaching response or biological potential. This review argues that such a static interpretation is insufficient
where flow, reaction, microbial activity and structural change reorganize the medium during operation. The
reviewed literature shows that environmental reactive porous media behave as evolving, biologically active and
self-organizing process systems. Hydraulic redistribution, dissolution, precipitation, redox transformation, particle
retention, biofilm development and gas transfer generate trajectories that can lead either to attenuation and
functional stabilization or to clogging, bypass, passivation, remobilization and loss of contact. The paper develops
a process-engineering synthesis in which performance is interpreted as the trajectory of coupled state variables,
including hydraulic conductivity, connected porosity, residence-time distribution, accessible reactive capacity,
active surface, biomass architecture, redox state and gas-transfer accessibility. The central conclusion is that
environmental engineering should move from static material control toward trajectory management. Control is
conditional, not absolute: it requires observable or inferable state variables, diagnostic monitoring of active
feedbacks, admissible functional domains and operational levers capable of guiding endogenous porous-media
dynamics. This framework provides a common interpretation for attenuation, stabilization and control pathways
across waste-management systems, reactive barriers, biocovers and contaminated subsurface environments.