A plume to be remediated by PRB is 200m long,3m wide and 5m deep. The actual velocity of flow is 10m/year. The aquifer has a porosity of 0.3 and the contaminant of concern is PCE which will be dechlorinated using ZVI to vinyl chloride. Assume that the PCE will be rapidly converted to VC. The maximum concentration of PCE in the plume is 10mg/L and the remediation goal for VC is 2micro gram/L. The kinetics of VC degradation were observed to be first order with K=0.01/hr in the batch experiment in which ZVI was added qt 150g/L. The PRB will be designed with a mixture of ZVI(30%) and sand (70%) and is of continuous type. The porosity of the mixture is 0.35 and its bulk density is 2.8 kg/L.
calculate
1) the retention time
2) required width
3) mass of iron required
4) If PRB is a funnel and gate type and the gate is 10% of the width of plume with the depth as same, what is the thickness of PRB
5) mass of iron required in case of Q4
@Sreekanth reddy Peddireddy: According to my opinion the best solution would be to perform laboratory testing and the results of these tests use for design calculation of your PRB. The tests also tell you what will be the rest concentration of PCE, TCE, DCEs. Their concentration will be hardly zero after ZVI treatment.
Goos luck
Vit
Hi,
You are best to re-write your 1st order degradation eqn in terms of half life (H=ln(2.0)/k). you will end up with C(t)=Ci(0.5^(t/H)). Therefore you can work out how long required to degrade the TCE.
The required width =groundwater velocity x residence time.
mass of iron can then be calculated assuming PRB dimensions and the required ZVI loading and the final specification of the wall (30% ZVI)
Application of a funnel and gate will require some other assumptions as the groundwater velocity increases in this setup. Therefore your wall will have to be thicker satisfy the 1st order degradation retention time. Be careful here, you should refresh your mind on Darcy Velocities.
I don't want to give specific calcs etc. as this seems like an assignment question. Try looking at some text books like Geochemistry, Groundwater and pollution by Appello and Postma, this text has many good examples for groundwater contamination.
Regards,
Brett