Study On The PRB Technology And Analysis Of Its Engineering Effectiveness For The Remediation Of Riverside Groundwater Contaminated By Ammonium

Riverside source fields are important for water supply in northern China, wherethe ammonia pollution problems caused by human activity and surface waterpollution have become increasingly serious. As an effective groundwater pollutionremediation technology, Permeable Reactive Barrier (PRB) is getting more and moreattention for its non-power operation, less environmental impact and low maintenancefeatures. However, it is difficult for the PRB’s application in riverside areacharacterized by high permeability, complex redox conditions. For the riversidegroundwater contanminated by ammonia, we have developed a composite mediumPermeable Reactive Barrier remediation techniques, to achieve effective removal ofammonia nitrogen in groundwater near the river. The technology has been appliedsuccessfully in a demonstration project. Main research results of this paper aredescribed in detail as following:(1) For the high permeability characteristics of unconfined aquifer of riversidewater source area, we have developed a zeolite with high adsorption capacity, largeparticle size, high permeability as the reaction medium of the PRB, to solve theproblem of less intercept width of groundwater flow and shorter residence time ofcontaminant in the riverside PRB. The permeability coefficient (K) of contaminatedaquifer in the study area is60-80m/d. The zeolite particles screened in the study are3-5mm diameter, and with permeability of700-800m/d, which adsorb ammonia withthe "rapid adsorption, slow equilibrium" characteristic. The maximum amount ofsaturated ammonia adsorption is up to9.30mg/g.(2) For reduction environmental of groundwater in the study area is notconducive to ammonia nitrification, we have has developed a Permeable ReactiveBarrier technology with release oxygen compound and zeolite as its compositemedium, which can effectively promote the nitrification of ammonia by changing thegroundwater redox environment. Experiments showed that the PRB with the oxygenrelease compound and zeolite materials as reaction medium can effectively removeammonia, with a decrease from10mg/L for influent concentrations to less than0.5 mg/L for effluent concentrations of. The removal efficency can reach90%. Relative tothe only river sand or zeolite as the medium, oxygen release compound can promotethe microbial reaction of ammonia by releasing oxygen, realize the regeneration ofzeolite, and avoid the secondary pollution caused by the desorption of ammonia.(3) The study constructed a Permeable Reactive Barrier remediationdemonstration project with composite medium to resolve the problem of groundwatercontaminated by ammonia in Liguanpu water source in Shenyang. Monitoring datashow that PRB demonstration project along River worked well. The ammoniaconcentration in groundwater can be decreased from2-10mg/L to0.5mg/L or less,meeting the "Sanitary standard for drinking water".The PRB developed in this paper, less affected by permeability of aquifer andredox environmental of groundwater, can effectively removes ammoniacontamination of groundwater near the river. The successful demonstration projectexpands the range of application of PRB technology, which will greatly promote theresearch and application of groundwater remediation technologies in China.