Evaluation of Amendments to Control Phosphorus Losses in Runoff from Pig Slurry Applications to Land

If spread in excess of crop requirements, incidental phosphorus (P) losses from agriculture can lead to eutrophication of receiving waters. The use of amendments in targeted areas may help reduce the possibility of surface runoff of nutrients. The aim of this study was to identify amendments which may be effective in reducing incidental dissolved reactive phosphorus (DRP) losses in surface runoff from land applied pig slurry. For this purpose, the DRP losses under simulated conditions across the surface of intact grassland soil cores, loaded with unamended and amended slurry at a rate equivalent to 19 kg P ha^?1, were determined over a 30 h period. The effectiveness of the amendments at reducing DRP in overlying water were (in decreasing order): alum (86%), flue gas desulfurization by‐product (FGD) (74%), poly‐aluminum (Al) chloride (PAC) (73%), ferric chloride (71%), fly ash (58%), and lime (54%). FGD was the most costly of all the treatments (€7.64/m³ for 74% removal). Ranked in terms of feasibility, which takes into account effectiveness, cost, and other potential impediments to use, they were: alum, ferric chloride, PAC, fly ash, lime, and FGD.     

River bank filtration in Haridwar, India: removal of turbidity, organics and bacteria

Improvement in the quality of river water filtered through a 17-m thick sand-gravel unconfined aquifer at a production well surrounded by surface-water bodies, in Haridwar (India), was studied. Distances between surface water sources and the production well are more than 115 m, and the shortest travel times are 77 and 84 days for monsoon and non-monsoon periods, respectively. During the monsoon period, surface water exhibited increased turbidity by 50–100 times, bacterial count of around 10 times and decreased electrical conductivity of around 0.6 times compared to non-monsoon samples. The quality of abstracted bank filtrate, however, was found not to significantly vary. In non-monsoon months, riverbank filtration resulted in a reduction of turbidity and coliforms by 1 and 3 logs, respectively. For monsoonal months, this increased to more than 2 and 4 logs in turbidity and coliforms reduction, respectively. UV absorbance was also found to be reduced to about 1 log during monsoon season. Results from column studies confirmed that a retention time of around 5 days is adequate to achieve more than 99.9% removal of coliforms.