Preliminary bench‐ and pilot‐scale investigations showed that coagulation is a promising treatment for removing arsenic from drinking water but that further work is needed, primarily on full‐scale plants. The possible use of enhanced coagulation for arsenic removal was examined at the facilities of a California utility in 1992 and 1993. The tests were conducted at bench, pilot, and demonstration scales, with two source waters. Alum and ferric chloride, with cationic polymer, were investigated at various influent arsenic concentrations. The investigators concluded that for the source waters tested, enhanced coagulation could be effective for arsenic removal and that less ferric chloride than alum, on a weight basis, is needed to achieve the same removal.

Gossypol, a natural polyphenolic compound extracted from cottonseed oil, has been reported to possess pharmacological properties via modulation cell cycle and immune signaling pathway. However, whether gossypol has anti-inflammatory effects against phytohemagglutinin (PHA)-induced cytokine secretion in T lymphocytes through similar mechanism remains unclear. Using the T lymphocytes Jurkat cell line, we found that PHA exposure caused dramatic increase in interleukin-2 (IL-2) mRNA expression as well as IL-2 secretion. All of these PHA-stimulated reactions were attenuated in a dose-dependent manner by being pretreated with gossypol. However, gossypol did not show any in vitro cytotoxic effect at doses of 5-20 μM. As a possible mechanism underlying gossypol action, such as pronounced suppression IL-2 release, robust decreased PHA-induced phosphorylation of p38 and c-Jun N-terminal kinase expressions was found with gossypol pretreatment, but not significant phosphorylation of extracellular signal-regulated kinase expression. Furthermore, gossypol could suppress the Jurkat cells' growth, which was associated with increased percentage of G1/S phase and decreased fraction of G2 phase in flow cytometry test. We conclude that gossypol exerts anti-inflammatory effects probably through partial attenuation of mitogen-activated protein kinase (phosphorylated JNK and p38) signaling and cell cycle arrest in Jurkat cells.

A direct ion chromatography method was applied to the determination of short-chain carboxylic acids (acetic, formic, and oxalic) in drinking water treated with ozone. These organic acids were separated on an anion exchange column (Ionpac AS11; Dionex Corp., Sunnyvale, CA), using a 50-μL sample loop. Samples were collected from the ozone pilot plant of the Metropolitan Water District of Southern California to study the formation of carboxylic acids and their removal by two differ ent types of biologically active filters. Preliminary results indicate that the carboxylic acid concentrations out of the ozone contactor were the greatest for oxalic acid (-380 μg/L), followed by formic (-130 μ/L) and acetic (-60 μg/L) acid, and that the sum of the three acids on a carbon basis was -160 μg/L. Approximately 80 percent of these car boxylic acids were removed during biofiltration. Aldehydes and assim ilable organic carbon (AOC) were also measured from the same batch of samples, and the removal percentages were similar to those obtained in the carboxylic acid analyses. The percent fractions of AOC at the ozone effluent for combined carboxylic acids and combined aldehydes were 36.9 and 3.7 percent, respectively.Because of concerns about health effects and regulations governing chlorination by products, the Metropolitan Water District of Southern California (MWDSC) and many other water agencies and utilities are actively investigating alternative disinfectants, such as ozone, to replace chlorine. The various by-products produced by the applica tion of ozone are being extensively studied (7). Furthermore, the ozonation of natural organic matter in the source water can produce smaller and more biodegradable or ganic compounds, collectively referred to as assimilable organic carbon (AOC), which can be used as nutrients for bacteria and may cause microbial regrowth problems in a water distribution system (2-4).