ESEL Paper Review_20110810
By Hong Guo
1,Title and Author
Title: Phosphorus removal by acid mine drainage sludge from secondary effluents of municipal wastewater treatment plants.
Xinchao Weia,*，Roger C.Viadero Jr.b, Shilpa Bhojappaa
a Department of Civil and Environmental Engineering, West Virginia University, PO Box 6103, Morgantown, Wv 26506, USA
b Western Illinois University, Institute for Environmental Studies, 1 University Circle, Macomb,Il 61455, USA
2. Summary of Paper
In this paper, the author used the Acid mine drainage(AMD) sludge to be as the absorbent to develop a cost effective treatment approach to phosphorus removal from municipal secondary effluents. The effects of pH, temperature, concentration are the key factors in the both of the batch test in the lab scale and CSTR in the real plant.
1, pH: system pH during adsorption has a significant effect on the surface characteristics of the adsorbent particles, overall adsorption performance. The effluent p concentration increased with an increasing pH, indicating orthophosphate adsorption by AMD sludge was inhibited at high pH.
2, Temperature: a decrease in effluent P concentration can be observed at higher temperature. Consequently the amount of phosphorus adsorbed by AMD sludge increased with temperature.
3, Sludge dose and contact time: the effluent P concentration decreased rapidly when the AMD sludge dose increased from low doses to 1.0g/L, where an effluent concentration of 1.02mg P/L was achieved. If the sludge was increased above 1.0g/L,, the decrease in effluent P concentration was trivial.
For the contact time, we can see that the first 5min the P removal was observed to the 89%. After then the gradual decrease in effluent P concentration occurred as mixing time was increased up to 1h. Mixing time was trivial after 1h here.
The change in CSTR effluent P concentration over time for three different waters (synthetic waste-water, Mon River water, and secondary effluent from a POTW (publicly owned treatment works)).the system reached equilibrium in about 3h, and pH remained constant at 7.3, 7.7 and 7.8 for 3 types of the water after 1 hr. then the effluent P concentration decreased from 20ppm to the 2ppm and for the equilibrium point it decreased 1ppm level.
This paper also shows the ideas for the phosphorus removal system using AMD sludge in the different types of treatment.
1, typical suspended growth secondary treatment
2, AMD sludge adsorption tertiary treatment added to a typical suspended growth system
3, Integration of AMD sludge-based adsorption into secondary treatment.
These 3 types of the ideas need to be verified by the further technical demonstration in pilot field studies to full assess the effects of variability of sludge sources, operational practicalities, waste disposal, treatment cost benefit tradeoff, and related regulatory issues.
Even though the project I am doing now does not used the AMD sludge, but we can see that the sludge reuse is also very important and hot issue for the water treatment management yesterday, today and future. The effective use of sludge not only gives us the cost-saving but also benefit to the environment. Moreover, the smart water grid also point out the importance of the sludge treatment.
ESEL Paper Review_20110810