TREATING ACIDITY IN COAL PIT LAKES USING SEWAGE AND ...

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McCullough, Lund and May (2008)
Sewage, greenwaste, and sediment samples were digested using aqua-regia as per (USEPA,
1995). The digestate and water samples were analysed by Inductively Coupled Plasma
Atomic Emission Spectrophotometry (ICP-AES) for Al, As, B, Ca, Cd, Cr, Co, Cu, Fe, Pb,
Mg, Hg, S, Se, Si, Sn, Zn. Total Kjeldahl N and Total P were measured in sewage and
greenwaste samples as per APHA (1998). Total Organic C was measured in sewage and
greenwaste samples on a TOC Analyser 700 (OI Corporation). Water samples were subject to
a persulfate digestion and analysed for TFN and TFP as per APHA (1998). All analyses were
undertaken at NATA accredited commercial laboratories.
The potential for human health risks associated with a field trial of the approach were
assessed by measuring faecal coliforms and gas production. Faecal Coliforms were measured
in the water of the microcosms on day 180 by the standard total coliform membrane filter
procedure for total members of the coliform group (APHA, 1998). Sample blanks and 10 mL
samples of microcosm surface water were taken with sterile 10 mL syringes, filtered with
20 mL sterile buffered water onto sterile gridded filters and then placed upon sterile
rehydrated agar pads staining for total coliforms (Sartorius AG 14053 N, ‘endo media’).
Coliform colonies were counted following 24 h dark incubation at 35 oC. The concentrations
of emitted gases (ammonia and hydrogen sulfide) were measured in the capped headspace on
days 8, 74 and 125. A single sample (400 mL) was collected from each replicate for controls
(only 3 sampled) and 200g treatments and combined for a total of 1.2 L which was pumped
through Draeger tubes for both gas types (levels of detection to 0.8 ppm).
7.2.1 Statistical analyses
Differences between treatments’ chemistry was determined by ANOVA with pair-wise
differences determined by Tukey’s Honestly Significant Difference (HSD) post hoc test
(Tukey, 1953). Multivariate physico-chemical data from day 180 was analysed by ANalysis-
Of-SIMilarity (ANOSIM) (Clarke, 1993) and Principal Components Analysis (PCA) in the
PRIMER 6 software package (PRIMER-E Ltd, 2001).