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Emerging remediation technologies such as chemical amendment of dairy cattle slurry have the 29 potential to reduce phosphorus (P) solubility and consequently reduce P losses arising from land 30 application of dairy cattle slurry. The aim of this study was to determine the effectiveness of 31 chemical amendment of slurry to reduce incidental losses of P and suspended sediment (SS) 32 from grassland following application of dairy cattle slurry and to examine the effect of 33 amendments on metal concentrations in runoff water. Intact grassed-soil samples were placed in 34 two laboratory runoff boxes, each 200-cm-long by 22.5-cm-wide by 5-cm-deep, before being 35 amended with dairy cattle slurry (the study control) and slurry amended with either: (i) alum, 36 comprising 8% aluminium oxide (Al2O3) (1.11:1 aluminum (Al):total phosphorus (TP) of slurry) 37(ii) poly-aluminum chloride hydroxide (PAC) comprising 10% Al2O3 (0.93:1 Al:TP) (iii) 38 analytical grade ferric chloride (FeCl2) (2:1 Fe:TP), (iv) and lime (Ca(OH)2) (10:1 Ca:TP). When 39 compared with the study control, PAC was the most effective amendment, reducing dissolved 40 reactive phosphorus (DRP) by up to 86% while alum was most effective in reducing SS (88%), 41 TP (94%), particulate phosphorus (PP) (95%), total dissolved phosphorus (TDP) (8 1%), and 42 dissolved unreactive phosphorus (DUP) (86%). Chemical amendment of slurry did not appear to 43 significantly increase losses of Al and Fe compared to the study control, while all amendments 44 increased Ca loss compared to control and grass-only treatment. While chemical amendments 45 were effective, the reductions in incidental P losses observed in this study were similar to those 46 observed in other studies where the time from slurry application to the first rainfall event was 47 increased. Timing of slurry application may therefore be a much more feasible way to reduce 4 48 incidental P losses. Future work must examine the long-term effects of amendments on P loss to 49 runoff and not only incidental losses. Land application of dairy cattle slurry can result in incidental and chronic phosphorus (P) losses 57 to a waterbody (Buda et al., 2009), which may lead to eutrophication (Carpenter et al., 1998). 58Incidental P losses take place when a rainfall event occurs shortly after slurry application and 59 before slurry infiltrates the soil, while chronic P losses are a long-term loss of P from soil as a 60 result of a build-up in soil test P (STP) caused by application of inorganic fertilisers and manure 61 (Buda et al., 2009). Incidental P losses arising from rainfall events following land application of 62 dairy cattle slurry are the focus of this study. 6364 examined the results of a number of studies examining P losses following 65 land application of dairy cattle slurry at different rates and under different climatic conditions 66 (Smith et al., 2001a;Withers et al., 2001;Withers and Bailey, 2003) and found that incidental P 67 losses can account for between 50 and 90% of P losses from land to w...

Land application of dairy slurry can result in incidental losses of phosphorus (P) to runoff in addition to increased loss of P from soil as a result of a buildup in soil test P (STP). An agitator test was used to identify the most effective amendments to reduce dissolved reactive phosphorus (DRP) loss from the soil surface after land application of chemically amended dairy cattle slurry. This test involved adding slurry mixed with various amendments (mixed in a beaker using a jar test flocculator at 100 rpm), to intact soil samples at approximate field capacity. Slurry/amended slurry was applied with a spatula, submerged with overlying water and then mixed to simulate overland flow. In order of effectiveness, at optimum application rates, ferric chloride (FeCl2) reduced the DRP in overlying water by 88%, aluminium chloride (AlCl2) by 87%, alum (Al2(SO4)3·nH2O) by 83%, lime by 81%, aluminium water treatment residuals (Al‐WTR; sieved to <2 mm) by 77%, flyash by 72%, flue gas desulphurization by‐product by 72% and Al‐WTR sludge by 71%. Ferric chloride (€4.82/m3 treated slurry) was the most cost‐effective chemical amendment. However, Al compounds are preferred owing to stability of Al–P compared with Fe–P bonds. Alum is less expensive than AlCl2 (€6.67/m3), but the risk of effervescence needs further investigation at field‐scale. Phosphorus sorbing materials (PSM) were not as efficient as chemicals in reducing DRP in overlying water. The amendments all reduced P loss from dairy slurry, but the feasibility of these amendments may be limited because of the cost of treatment.

Landfill leachate is the result of water percolating through waste deposits that have undergone aerobic and anaerobic microbial decomposition. In recent years, increasingly stringent wastewater discharge requirements have raised questions regarding the efficacy of co-treatment of leachate in municipal wastewater treatment plants (WWTPs). This study aimed to (1) examine the co-treatment of leachate with a 5-day biochemical oxygen demand (BOD): chemical oxygen demand (COD) ratio less than or slightly greater than 0.26 (intermediate age leachate) in municipal WWTPs (2) quantify the maximum hydraulic and mass (expressed as mass nitrogen or COD) loading of landfill leachate (as a percentage of the total influent loading rate) above which the performance of a WWTP may be inhibited, and (3) quantify the impact of a range of hydraulic loading rates (HLRs) of young and intermediate age leachate, loaded on a volumetric basis at 0 (study control), 2, 4 and 10% (volume landfill leachate influent as a percentage of influent municipal wastewater), on the effluent ammonium concentrations. The leachate loading regimes examined were found to be appropriate for effective treatment of intermediate age landfill leachate in the WWTPs examined, but co-treatment may not be suitable in WWTPs with low ammonium-nitrogen (NH-N) and total nitrogen (TN) emission limit values (ELVs). In addition, intermediate leachate, loaded at volumetric rates of up to 4% or 50% of total WWTP NH-N loading, did not significantly inhibit the nitrification processes, while young leachate, loaded at volumetric rates greater of than 2% (equivalent to 90% of total WWTP NH-N loading), resulted in a significant decrease in nitrification. The results show that current hydraulic loading-based acceptance criteria recommendations should be considered in the context of leachate NH-N composition. The results also indicate that co-treatment of old leachate in municipal WWTPs may represent the most sustainable solution for ongoing leachate treatment in the cases examined.

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