Author(s): Alvaro Munoz; Polioptro Martinez
Linked Author(s): Polioptro F. Martínez Austria
Keywords: Coastal lagoons; Restoration; Aeration; Forced circulation
Abstract: The Bojorquez lagoon forms part of the Nichupte lagunar system in the Mexican Caribbean sea. Tourist and urban development has resulted in low intensity, long term, water and sediment pollution. In order to reverse this situation, the National Water Commission and other government institutions took certain actions, such as the relocation of the municipal refuse site away from the lagoon, improvements in the operation and maintenence of treatment plants and law enforcement to stop direct raw-wastewater discharges into the lagoon. There has been a significant improvement in water quality in the underwater springs which are the result of the karst-type geological characteristics of the subsoil and the hydrological connections with underground acquifers. The water and sediment at Bojorquez lagoon, however, has not shown a significant improvement. In order to solve this problem, three aeration systems were conceptually designed in 1995, constructed during 1997 and tested at the beginning of 1998. The systems worked as expected, with the exception of the jet penetration depth, which would eventually reach approximately half of the water depth at the most, thus reducing the reoxygenation process efficiency. An additional discharge pit structure is proposed, including a set of radial diffusers which in turn could improve the discharge of high DO content water near the watersediment interphase. Results from hydrodynamics, DO and BOD transport numerical simulations indicated that a significant improvement in these parameters could be expected after six months of continuous operation of the aeration systems. Factors affecting the DO balance in a lagunar natural cycle are presented and the possibility of using them as indicators of trophic tendencies suggested.
Year: 1999