Application of UF and RO for Mine Wastewater Reuse

E Shao, J Wei ,A Yo and R Levy


copper_mine The copper mine wastewater has high level of TDS, chemical oxygen demand (COD), hardness and total suspended solids (TSS), as well as high concentrations of SO4, silica, iron and other metals. The raw wastewater fluctuates greatly, which make the water extremely challenging to purify. Typical feed water quality is shown in Table 1.
The main challenges from copper mine waste water treatment:
  • High level of chemical oxygen demand (COD);
  • High level of total suspended solids (TSS);
  • High salinity;
  • High concentration of silica, sulfate, iron and other contaminants; and fluctuation of raw water quality.
Table 1. Feed water quality of the Chile copper mine wastewater treatment.
Parameter Unit Value
Conductivity µS/cm 10 000 - 20 000
Total suspended solids (TSS) mg/l 100 - 800
Turbidity NTU 100 - 500
Chemical oxygen demand (COD) mg/l 1000 - 2000
Silica mg/l 20 ~ 50
Sulphate mg/l 5000
Total alkalinity mg/l 500
Calcium mg/l 330
The main advantages of UF membrane technology as pretreatment of RO are (Yeunget al, 2008; Fanget al, 2003):
  • Stable quality of UF permeate independent of raw water quality.
  • Low silt density index (SDI) and turbidity of the UF permeate. UF can reliably provide RO feed water with SDI <3 and Turbidity <0.1 NTU, even in difficult feed water.
  • Reliable removal of bacteria and viruses by UF, reducing bio-fouling of the RO membranes.
  • UF units and plants are highly automated, including membranes backwash and chemical cleaning.
  • UF systems are flexible in their performance and can handle changing qualities and flows.
  • High reliability of operation-UF membranes act as ‘absolute barrier’ that can be tested for very fine integrity breaches
coal mining

The main challenges from coal mine waste water treatment:

  • High level of total dissolved solids,
  • Waste water quality fluctuation
Parameter Unit Value Parameter Unit Value
K+ + Na+ mg/l 1440.62 NO2- mg/l 3.94
Ca2+ mg/l 559.44 PO43- mg/l 6.5
Mg2+ mg/l 232.72 Total hardness mg CaCO3/l 4704.5
Fe2+ mg/l 0 Oil mg/l 5-10
NH4+ mg/l 1 pH - <8
Cl- mg/l 481.32 SiO2 mg/l 14
SO42- mg/l 4240.72 COD mg/l <5
HCO3- mg/l 30 TSS mg/l <20
CO32- mg/l 16.8 TDS mg/l 8458
NO3- mg/l 3.2