Direct Injection of Reclaimed Water Into an Aquifer

Retardation of ammonium and potassium transport through a contaminated sand and gravel aquifer: the role of cation exchange

“…Baedecker et al (17) observed that concentrations of NH4+ relative to N03" decreased with increasing distance from a landfill and attributed the observed attenuation of NH4+ to cation exchange onto aquifer clay particles. Changes in groundwater NH4+ concentrations due to cation exchange have also been noted in recharge experiments (19,20). Although these studies found distribution patterns of NH4+ and N03" similar to those at the Cape Cod study site, the aquifers contained significant amounts (2-10%) of clay (20) or clay lenses (17,19), whereas the Cape Cod site is a sand and gravel aquifer with generally <0.1% clay (25).…”

“…Changes in groundwater NH4+ concentrations due to cation exchange have also been noted in recharge experiments (19,20). Although these studies found distribution patterns of NH4+ and N03" similar to those at the Cape Cod study site, the aquifers contained significant amounts (2-10%) of clay (20) or clay lenses (17,19), whereas the Cape Cod site is a sand and gravel aquifer with generally <0.1% clay (25). However, Dance and Reardon (23) have shown that cation-exchange processes can account for a large portion of the observed groundwater chemistry even in coarse-grained aquifers with low clay content.…”

“…Although N03~i s generally absent in anaerobic contaminant plumes due to biological reduction to N2, N20, or NH4+ (14), it is persistent in oxidized groundwater and is often mobile, because of its high solubility and minimal sorption (15). The transport of NH4+, however, may be retarded by its chemical sorption properties (sorption is used here to describe both adsorptive and ion-exchange reactions) (16)(17)(18)(19)(20).…”

“…Few studies have directly investigated the effect of cation exchange on NH4+ transport in groundwater. For the most part, these studies were of aquifers containing a substantial proportion of clay (17,19,20). However, results of a recent natural-gradient tracer study (23), and a study of groundwater contaminant distributions (24) indicated that the influence of cation exchange may be significant in sand and gravel aquifers that have relatively low clay content (less than 1.0%).…”

Molecular weight distribution of dissolved organic carbon and dissolved organic halogen in advanced treated wastewaters

“…Sampling Sites at the Palo Alto Water Reclamation Facility. During this investigation the Palo Alto Water Reclamation Facility (PAWRF) treated chlorinated secondary effluent with lime clarification, ammonia stripping, recarbonation, filtration, ozonation, activated-carbon adsorption, filtration, and chlorination (34). The effluent was chlorinated typically with 2 mg/L and was injected directly into a confined aquifer.…”