Algae ͑green, blue-green, and diatom͒ grown in inorganic media produced particulate and dissolved organic carbon ͑DOC͒. DOC produced by a green-alga contains 25% hydrophobic acids. DOC from all algae had specific ultraviolet absorbance values less than 2.0 m −1 ͑mg/ L͒ −1. Algae-produced DOC was biologically labile; greater than 60% degraded in bioreactors within 5 days. The biodegradable material likely included carbohydrates, amino acids, and amino sugars, which were present in hydrophobic acid isolates. Chlorination of algal DOC formed disinfection by-products; DOC from the green alga, Scenedesmus quadricauda, produced chloroform ͓0.53 micromole per mg carbon ͑mol/ mg C͔͒, dichloroacetic acid ͑0.27 mol/ mg C͒, and trichloroacetic acid ͑0.14 mol/ mg C͒. This work complements other studies, which focused on algal total organic carbon ͑DOC and cellular material͒, and clearly demonstrates the importance of identifying algae-derived sources of DOC in water supplies and removing such DOC in water treatment plants prior to chlorination.

This study investigated the optimal reaction conditions for biodiesel production from soursop (Annona muricata) seeds. A high oil yield of 29.6% (w/w) could be obtained from soursop seeds. Oil extracted from soursop seeds was then converted into biodiesel through two-step transesterification process. A highest biodiesel yield of 97.02% was achieved under optimal acid-catalyzed esterification conditions (temperature: 65 °C, 1% H2SO4, reaction time: 90 min, and a methanol:oil molar ratio: 10:1) and optimal alkali-catalyzed transesterification conditions (temperature: 65 °C, reaction time: 30 min, 0.6% NaOH, and a methanol:oil molar ratio: 8:1). The properties of soursop biodiesel were determined and most were found to meet the European standard EN 14214 and American Society for Testing and Materials standard D6751. This study suggests that soursop seed oil is a promising biodiesel feedstock and that soursop biodiesel is a viable alternative to petrodiesel.

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Horseshoe Reservoir, shown in this aerial view, is part of a reservoir system that is used as the primary raw drinking water supply for cities in the metropolitan Phoenix, Ariz., area.Regulations for disinfection by-products (DBPs) will be expensive to meet through modifications in water treatment technology alone. An adjunct DBP control strategy is to reduce concentrations of DBP precursors in source waters.

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