The efficiency of various polyaluminium chloride coagulants (PACls) was compared to the efficiency of aluminium sulfate (alum) in the coagulation-flocculation process preceding direct filtration in drinking water treatment. The comparative study consisted of two separate yet complementary series of experiments: the first series included short (5-7 h) and long (24 h) filter runs conducted at a pilot filtration plant equipped with large filter columns that simulated full-scale filters. Partially treated surface water from the Sea of Galilee, characterized by very low turbidity (-1 NTU), was used. In the second series of experiments, speciation of aluminium in situ was investigated using the ferron assay method. Results from the pilot-scale study indicate that most PACls were as or more efficient a coagulant as alum for direct filtration of surface water without requiring acid addition for pH adjustment and subsequent base addition for re-stabilizing the water. Consequently, cost analysis of the chemicals needed for the process showed that treatment with PACl would be significantly less costly than treatment with alum. The aluminium speciation experiments revealed that the performance of the coagulant is more influenced by the species present during the coagulation process than those present in the original reagents.

East Bay Municipal Utility District (EBMUD) conducted a pilot study to demonstrate the production and use of biodiesel from interceptor grease waste. Bench-scale testing was followed by pilot-scale production of 200 to 400-L batches. Brown grease with a free fatty acid (FFA) content of 54-100% was obtained from interceptor grease hauled to EBMUD's wastewater treatment plant. Free fatty acids were converted using a one or two step acid esterification reaction and triglycerides were converted using a sodium methoxide catalyzed transesterification reaction, both at ambient temperatures. Impurities associated with the brown grease, such as sulfur, proved to be problematic. Biodiesel was used to fuel heavy duty diesel trucks as B20 and B100 for multiple weeks. No operational or performance problems were reported. Preliminary energy and economic comparison to anaerobic digestion show a more favorable energy balance for biodiesel and a potentially more favorable economic value for biodiesel, but with significant risk.