Coupled photochemical-biological system to treat biorecalcitrant wastewater

The aim of the present work is to study a coupled system to treat biorecalcitrant wastewaters. The combination consists of an advanced oxidation process (AOP) named photo-Fenton (Ph-F), which is a photochemical treatment and a sequencing batch biofilter reactor (SBBR). The synthetic wastewater used to optimise this process is a solution of 200 ppm of 4-chlorophenol (4-CP). The first part of the work is the study of the biodegradability enhancement achieved by the photochemical process, measured as the ratio between the biochemical oxygen demand (BOD5) and the chemical oxygen demand (COD). The second step is the start-up and optimisation of the biological process. The results showed that it is necessary to severely treat the toxic solution (with 500 ppm of [H2O2]0) in order to achieve more than 90% of TOC removal in the whole process. The photochemical and biological treatments lasted 50 minutes and 24 hours, respectively.

Changes in plasma lipoproteins and liver lipids in neonatal rats

Transient increases in triglycerides and cholesterol were found in rat liver immediately after birth. Plasma VLDL and HDL increased after birth and reached a plateau after one week of life. The content of cholesterol ester was low at birth in all lipoproteins and increased in LDL and HDL during the first week of life. After birth, VLDL became enriched in apolipoproteins C and E, whereas HDL was enriched in apolipoprotein C and depressed in apolipoprotein E. The developmental changes in plasma lipoprotein levels and compositions in rats during the first week of life are comparable to those described in humans.

Regulation of hepatic cholesterogenesis by polar steroids accumulated after cholesterol feeding

The incorporation of mevalonate into nonsaponifiable lipids by chick liver in vivo strongly increased between 1-18 days after hatching. Cholesterol feeding (2%) inhibited this. Synthesis of cholesterol was strongly inhibited, whereas the intermediates isolated by TLC accumulated. Most of the polar nonsaponifiable lipids that accumulated in liver 90 minutes after mevalonate administration to 18-day-old cholesterol-fed chicks were identified as lanosterol derivatives. 3-Hydroxy-3-methylglutaryl-CoA reductase activity, as well as acetate and mevalonate incorporation into nonsaponifiable lipids, was inhibited by the presence of these compounds. To our knowledge, this is the first report of such inhibition; this confirms the physiological function of polar steroids in the regulation of cholesterogenesis in vivo.