Identification of a Carboxyl group at the Active Site of Barley MaIt Phosphatase

The dependence of the maximal velocity, Vm with pH for barley malt phosphatase has been studied from pH 4.0 to 5.4. The data show that an ionizable group in the enzyme-substrate complex with a pK2 of 4-4.6 is important for enzymic activity. These results suggest strongly the involvement of a carboxyl group of a glutamic or aspartic acid residue at the active site of this enzyme

Long-Term Field Performance of Biosand Filters in the Artibonite Valley, Haiti

A field study assessing the sustainability and efficacy of 55 biosand filters installed during 1999–2010 was conducted in the Artibonite Valley, Haiti during 2011. Twenty-nine filters were still in use. Duration of filter use ranged from \u3c 1 to 12 years. Water quality, microbial analysis, and flow rate were evaluated for each functioning filter. Kaplan- Meier analysis of filter lifespans showed that filter use remained high (\u3e 85%) up to seven years after installation. Several filters were still in use after 12 years, which is longer than documented in any previous study. Filtered water from 25 filters (86%) contained Escherichia coli concentrations of \u3c 10 most probable number of coliforms/100 mL. Recontamination of stored filtered water was negligible. Bacterial removal efficiency was 1.1 log10. Comparable results from previous studies in the same region and elsewhere show that biosand filter technology continues to be an effective and sustainable water treatment method in developing countries worldwide