Water geothermal waste

Oil, gas, and geothermal wastes. Certain wastes from the exploration and production of oil, gas, and geothermal energy are excluded from the definition of hazardous waste. These wastes include those that have been brought to the surface during oil and gas exploration and production operations, and other wastes that have come into contact with the oil and gas production stream (e.g., during removal of waters injected into the drill well to cool the drill bit). 

Depending on the winter climate, the heat source can be a lake, reservoir, underground storage tank, aquifer (underground river or lake), solar-heated water, sewage or waste water, geothermal energy or waste heat from industrial or commercial facilities. 

Einarsson, S. S., Vides, R. A. Cuellar, G. 1975. Disposal of geothermal waste water by reinjection In Proceedings Second United Nations Symposium on the Development and Use of Geothermal Resources, San Francisco, 20-29 May 1975, 1349-1363. 

Panichi, C. 2004. Geochemical impact of re-injecting geothermal waste waters Example Larderello, Italy. In Giere, R. Stille, P. (eds) Energy, Waste and the Environment a Geochemical Perspective. Geological Society, London. Special Publication 236, 337-354. 

Geochemical impact of re-injecting geothermal waste waters example, Larderello, Italy... 

Various methods for the removal of As from geothermal waste waters have been investigated at theoretical, laboratory, pilot plant and full plant scales. These include adsorption onto Fe-oxide floe and subsequent separation by dissolved air flotation (De Carlo and Thomas, 1985 Shannon et al., 1982) and co-precipitation with lime to form an As-rich calcium silicate (Rothbaum and Anderton, 1976). In both cases, effective removal was achieved only after oxidation of As" to As, For Fe-oxide floe treatment, competitive adsorption of silica inhibits As adsorption, particularly that of As" (Swedlund and Webster, 1999), suggesting that prior removal of silica would help optimise As removal efficiency. The use of ion selective chelating resins for As" removal from geothermal waters has also been successfully tried (Egawa et al, 1985). 

In the Palimpinon geothermal field in the Philippines, where waste fluid has been injected for some years, re-injected fluid has already returned into the production wells, as indicated by an increase in the salinity of the water produced. Harper Jordan (1985) report an increase in Cl concentration in a large number of production wells of the Palimpinon field. This response to re-injection was observed only three years after re-injection operations started. The increase in Cl is different for each of the production wells and reflects the amount of the reinjected fluid returning to each of the wells. 

Fig. 10. Zonation of the Larderello geothermal field derived from (a) gas analyses, and (b) stable isotope values of steam produced before and after re-injection. Distribution and characterization of geothermal subunits obtained by gas analyses have been established from a data set collected before 1989, that is, 6 years after the beginning of re-injection of waste waters. White zones represent areas that produce gas mixtures with almost the same composition as that of the original gases emerging at the surface before the exploitation of the field (Scandiffio et al. 1995). Dashed zones produce steam affected by addition of cold water (i.e., re-injected) to the geothermal system. The zonation from the isotopes was derived from an extensive survey performed in 1992. In Fig. 10b, different sources of cold water are discriminated. Abbreviations LRD = Larderello, CN = Castelnuovo, MR = Monterotondo, SS = Sasso Pisano, LGR = Lagoni Rossi, SR = Serrazzano geothermal subunits.

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