Management of Brine Disposal

The example shows that since pHc 8.4 (7.46 8.4), Ca2+ would precipitate as CaC03. From the analysis above, one can also calculate the SAR (Eq. 11.5)  

This calculated SAR can be used to estimate the adjusted SAR (adj.SAR), which describes Na+ potential in a CaC03-saturated solution to influence SAR. It is estimated 

The adj.SAR is greater than the SAR (12.22 vs. 6.3). This suggests that Ca2+ would precipitate as CaC03 and the adverse effects of Na+ on water quality would intensify. 

Three factors determine how much brine can be disposed of in a field, assuming that the brine does not contain boron. The first factor is the type of crop crown. Different crops tolerate different levels of salt. For example, some clovers are extremely sensitive to salt, while some grasses, like tall fescue, are quite tolerant (Table 11.2). The second factor is the CEC of the soil. A soil with a CEC of 10 meq 100 g-1 can tolerate approximately 460 lb of sodium per acre (10% of CEC) before it reaches its critical toxicity threshold. However, a soil with a CEC of 20 meq 100 g 1 can tolerate up to 920 lb of sodium per acre before it reaches its critical threshold. The third factor is the texture of the soil. A sandy soil can take very little sodium chloride salt before it 

TABLE 11.2. Crop Sensitivity to Salts, Based on the Saturation Extract Test 

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The siting, design, construction and management of any disposal option needs to be done to minimise negative environmental impacts. In some instances, there may be a trade off between desalination plant performance and the environmental suitability of the brine. Plants with high recovery rates that produce a more concentrated brine must have the means to dispose of this concentrate solution in a safe and environmentally friendly manner. When safe concentrate management is not achievable, the recovery of a plant may need to be compromised. 

The RCRA permit requirements and practices for disposal of brine are fairly uniform across the four baseline sites. There are no analytical issues preventing the accurate characterization of brines, and sites have had no problem meeting the waste control limits. Disposal options for brine solution and brine salts at off-site TSDFs are also readily available and utilized. A stricter requirement for on-site brine salt evaporation is enforced at UMCDF but has not impeded the overall waste management program at that site. 

Managing salt-affected soils or brackish waters in natural environments (e.g., land, streams, rivers, and lakes) requires knowledge of the chemistry of soil and brine, how brines interact with soil-water systems, and how these systems are affected by such interactions. This chapter deals with the practical aspects of Na+-Ca2+ exchange reactions and CaC03 solubility for the effective management of salt-affected soils and safe disposal of brines to soil-water environments. 

Recommcndation 4-1. To avoid the possibility of unanticipated disposal problems, the PMACWA and the BGCAPP contractor should characterize and consider waste management options for reverse osmosis rejectate brine, supercritical water oxidation (SCWO) filtrate solid waste, SCWO titanium tank liners, venturi scrubber particulate filters, and energetics offgas treatment system filters before submitting the waste analysis plan required by RCRA. The PMACWA should also look carefully for any as-yet-unidentified secondary waste streams from BGCAPP or PCAPP. 

Abstract This chapter discusses the characteristics of membrane concentrate, and the relevance that the concentrate has on the method of disposal. Membrane concentrate from a desalination plant can be regarded as a waste stream, as it is of little or no commercial benefit, and it must be managed and disposed of in an appropriate way. It is largely free from toxic components, and its composition is almost identical to that of the feed water but in a concentrated form. The concentration will depend on the type of desahnation technology that is used, and the extent to which fresh water is extracted from the brine. Based on the treatment processes that are used, a number of chemicals may also be present in the concentrate, albeit in relatively small quantities. 

Brines. Brines produced from air pollution control processes at Tooele are currently being shipped off site for disposal by conunerdal waste management facilities. The Army also plans to ship the effluent from SCWO (after concentration by evaporation) at Newport off site for disposal. This material has been delisted as a hazardous waste by the state of Indiana, and the Army has identified 16 commercial facilities that can accept the brine (Wojciechowski, 2000). Off-site managanent of SCWO effluent after evaporation (to recover water) would eliminate the need for a crystallizer and simpUly process integration at Pueblo. 

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