was made when PRHA was used. It was observed that pH was initially
increased with increase in PRHA doses and then decreased
when 16 g of PRHA was used; an increase in pH was further
observed at increasing PRHA dosage. The increase in the pH values
of treated water from both RHA could be due to the pH of the RHA,
though this is yet to be confirmed.
It was generally observed that the turbidity of the treated water
using both ash samples decreased with increase in pH values. A
report on the effect of pH control on turbidity removal from water
by Ashery et al. (2010) showed similar trend, according to the
authors maximum turbidity removal efficiency were obtained at
pH 5 and 6. On the contrary, Zhang et al. (2012) observed that
the turbidity removal from water increased when the wastewater
was alkalised, also, Mandal (2014) reported an optimum turbidity
removal at pH 8.51. In this present study, maximum turbidity
removal efficiency were observed at pH of 8.15 (3.70 NTU) and
7.55 (4.44 NTU) for water treated with URHA and PRHA
respectively.
Total dissolved solids were determined for the turbid raw water
and clarified treated water; the results are shown in Fig. 4. The TDS
of the clarified treated water generally increased compared to the
TDS of the raw water. Treated water obtained using URHA showed
higher TDS values in the range of 480–820 ppm while the TDS values
of treated water from PRHA were in the range of 270–530 ppm.