Excess Organic Matter Research Articles

The Effect of Fluorine on the Precipitation of Hydrous Iron Oxides from Groundwater Using Re-Infiltration

The behaviour of Fe, Si, Cu, Zn and F was studied in a plant constructed for purification of groundwater from excess Fe, Mn and organic matter by aeration and subsequent re-infiltration at Taivassalo, south-western Finland. The aquifer of the groundwater intake comprises the Laitila rapakivi area and the water has a relatively high F content. The groundwater purification plant consist of two units. In the pre-treatment unit the water was discharged onto a macadam contact filter for aeration, after which it flowed through two clarification basins to the infiltration basin of the re-infiltration unit. Fe oxidized during the treatment and precipitated as hydrous oxides. Precipitates were filtered from water and dried at 20°C, both immediately after sampling and after two year's aging in natural water at 4°C. To clarify the mode of occurrence of the elements the samples were subjected to extraction by 1 M ammonium acetate (NH4Ac) at pH 7.3 for exchangeable and loosely bound elements, at pH 4.8 for loosely bound and sorbed elements, by 1 M hydroxylammonium chloride plus 2 M acetic acid (HX1 - HAc) at 18°C for reducible loosely bound elements and Fe oxyhydroxides, and by HXl-HAc at 80°C for total Fe oxyhydroxide bound F. The precipitates were extracted with NH4Ac (pH 4.8) and HX1-HAc during different time intervals. The F content in water decreased along the flow path but increased during the re-infiltration step. The removal of F from water would obviously be more efficient if the plant arrangements like retention time were more suitable for this purpose. F and Si interacted strongly with Fe in the precipitates, preventing their ordering, and F, Si and Fe correlated well with each other. The loosely bound forms of these elements decreased along flow path and increased during aging of the precipitates. F and Cu were strongly, and Zn less strongly sorbed and scavenged by the precipitates. Owing to the relatively low pH of the raw water (5.74) Ca2+and other cations were not sorbed as was observed at higher pH's (over 7) and Cu and Zn were sorbed instead.

Presence of ciliate colonies on the exoskeleton of the freshwater crayfish Cherax tenuimanus (Smith) [Decapoda: Parastacidae

Dense colonies of the protozoan Epistylis sp. were found on the exoskeleton of one-year-old Cherax tenuimanus being reared at a commercial farm near Woongoolba, Qld. The ciliate has not been considered to be directly harmful to C. tenuimanus. Large colonies however were found covering pereiopods and maxillipeds, and extending to the brachiostegite and the ventral portion of the abdomen, and are believed to be responsible for the death by asphyxia of several crayfish. Probable causes of the ciliate bloom on the crustacean carapace are (i) a dramatic reduction in ecdysal frequency, related to temperature, (ii) bacterial blooms resulting from excessive organic matter in the pond, and (iii) the lack of alternative sites for colonization by the ciliate.

Bottom sediments in a polluted marine environment, upper Saronikos Gulf, Greece

The domestic and industrial waste water from most of the greater Athens, Greece area is discharged into shallow water at the upper end of the semi-enclosed Saronikos Gulf. The lack of circulation and excess organic matter has led to the formation of a rapidly expanding sludge field. Black anoxic sediments high in organic carbon now cover almost 9 sq km of sea floor and contain high concentrations of heavy metals. Maximum increases above background values range from 22× for mercury, 1500× for arsenic, 1200× for chromium, to 3000× for zinc. The principal sources of metals are 1) a fertilizer factory, 2) the Athens sewer outfall, and 3) the industries in eastern Elefsis Bay.

Treating Runoff from Agricultural Operations for Use As a Water Supply

ABSTRACT IN a 3 year study, the operation and input require-ments of various rural water treatment methods were investigated. Runoff was pretreated with sand filtration followed by treatments of chlorination, ozonation, or ultraviolet radiation. Results indicated that chlorination remains ef-fective and dependable, and that when chlorine, alone, can adequately treat water, it is a more practical solution than other treatments. Ozonation was im-practical for individual rural use. Ultraviolet radiation was effective in disinfecting water, but provided no treatment for excess organic matter or chemicals. Equipment investment for the various treatment facilities varied greatly, but operating costs were almost identical.