Page 266 - Membranes for Industrial Wastewater Recovery and Re-Use

Case studies 2 3 5

Figitre 5.4 (a) Microfiltratiori arid (b) reverse nsriiosispilotplarits at Eraririgpoa~erstcitiori

5.2.3 Performance
The plant is reported to have performed well since its installation and has
resulted in significant water savings. The percentage of reclaimed water used
has increased gradually from 5.2% during installation in 1994 to 56.7%) in 1998
such that up to February 1999 the plant has used a total of 2 3 3 3 M1 of reclaimed
water. In 1999, potable water use at the site was 1.8 M1 d-' and this is expected
to be ultimately reduced to 400 kl d-l by 2010 when the duration of the deed of
agreement is complete.
The treatment performance is indicated by a reduction in BOD from 20 to 50
to less than 1 mg 1-' across the whole plant (Table 5.20). The equivalent
removal for turbidity is from 50 to <0.1 NTU and for Faecal coliforms from
< 10' to < 1. RO permeate is also low in dissolved solids with a permeate
concentration of specific ions of 32 mg 1-' (Cl), 2.2 mg 1-1 (Si), 17.8 mg 1-' (Na)
and 0.5 mg 1-' (Ca). The low levels of dissolved solids have increased
demineraliser cation operation capacity from 2 176 m3 with potable water to
4792 m3 with reuse water and anion operation capacity from 2113 m3 to 3472
m respectively before requiring a regeneration.
The main operational concerns have been periods of increased membrane
fouling. At one stage the MF plant was not responding to the cleaning cycle.
Diagnosis revealed manganese fouling was occurring which was completely
ameliorated with a citric acid (citriclean) clean. Similarly, at one stage RO
cleaning frequency increased dramatically. The problem was linked to organic
fouling which decreased naturally as indicated by reduced chlorine demand and
ammonia levels in the plant. Ifthe problem occurs again a chlorine chemical clean
is planned to oxidise the organic layer. An important aspect of the scheme has
been gaining employee acceptance of using reclaimed water. To allay fears and
concerns regular testing for bacteria and viruses is reported and personal
protective equipment (ppe) and covers for equipment is supplied were appropriate.
The water reclamation plant originally required a total capital cost of
AUD$4.5 million($3.34million)in 1994ofwhichAUD$4million (S2.96million)
was construction and commissioning and AUD$0.5 million ($0.3 7 million) was
required for segregating the potable and reclaimed water supplies. A further