Abstract: Functional roles of Schoenoplectus californicus, giant bulrush, were evaluated in an 3.2 ha (8-acre) constructed wetland treatment system receiving copper-contaminated water. The constructed wetland used in this research was designed to decrease bioavailable copper concentrations in a wastestream and eliminate associated toxicity to downstream biota by exploiting the thermodynamic processes responsible for copper speciation. This was achieved by integrating carbon, sulfur and copper biogeochemical cycles. In this system, S. californicus, which represents an integral part of the carbon cycle, provides a physical, chemical and biological role in removing metals from the aqueous phase. The specific contributions of S. californicus in this system are to provide a sustainable carbon source for removal of copper by (1) provision of an organic ligand for sorption of copper entering the system, (2) production of organic ligands through growth of S. californicus, (3) accretion of organic ligands over time due to decomposition of S. californicus detritus, and (4) use of organic carbon as an energy source for dissimilatory sulfate production. Shoots and roots of viable S. californicus sorbed 0.88% and 5.88%, respectively, of copper entering the system. The half-life of S. californicus detritus in the constructed wetland system was approximately 184 d, indicating that sufficient detritus will accrete over time, providing binding sites for copper and an energy source for bacterial metabolic processes that contribute to copper immobilization in wetland systems.

Abstract: To study the functions of activated carbon and activated coke adsorption for the treatment of highly contaminated discolored industrial wastewater with a wide molecular size distribution of organic compounds, the deposited lignite pyrolysis wastewater from a filled open-cast coal mine was used for continuous and discontinuous experiments.

Abstract: Grootvlei Proprietary Mines Ltd is discharging between 80 and 100 Ml/d underground water into the Blesbokspruit. This water is pumped out of the mine to keep the underground water at such a level as to make mining possible. The water is of poor quality because it contains high TDS levels (2700-3800 mg/l) including high concentrations of iron, manganese, sulphate, calcium, magnesium, sodium and chloride. This water will adversely affect the water ecology in the Blesbokspruit, and it will significantly increase the TDS concentration of one of the major water resources if not treated prior to disposal into the stream. Therefore, alternative water desalination technologies were evaluated to estimate performance and the economics of the processes for treatment of the mine water. It was predicted that water of potable quality should be produced from the mine water with spiral reverse osmosis (SRO). It was demonstrated that it should be possible to reduce the TDS of the mine water (2000-2700-3400-4500 mg/l) to potable standards with SRO (85% water recovery). The capital costs (pretreatment and desalination) for a 80 Ml/d plant (worst-case water) were estimated at US$35M. Total operating costs were estimated at 88.1c/kl. Brine disposal costs were estimated at US$18M. Therefore, the total capital costs are estimated at US$53M. It was predicted that it should be possible to produce potable water from the worst-case feed water (80 Ml/d) with the EDR process. It was demonstrated that the TDS in the feed could be reduced from 4178 to 246 mg/l in the EDR product (65% water recovery). The capital costs (pretreatment plus desalination) to desalinate the worst-case feed water to potable quality with EDR is estimated at US$53.3M. The operational costs are estimated at 47.6 c/kl. Brine disposal costs were estimated at US$42M. Therefore, the total capital costs are estimated at US$95.3 M. It was predicted that it should be possible to produce potable water from the mine water with the GYP-CIX ion- exchange process. It was demonstrated that the feed TDS (2000- 4500 mg/l) could be reduced to less than 240 mg/l (54% water recovery for the worst-case water). The capital cost for an 80 Ml/d ion-exchange plant (worst-case water) was estimated at US$26.7M (no pretreatment). Operational costs were estimated at 60.4 c/kl. Brine disposal costs were estimated at US$55.1M. Therefore, the total desalination costs were estimated at US$81.8M. The capital outlay for a SRO plant will be significantly less than that for either an EDR or a GYP-CIX plant. The operating costs, however, of the RO plant are significantly higher than for the other two processes. Potable water sales, however, will bring more in for the RO process than for the other two processes because a higher water recovery can be obtained with RO. The operating costs minus the savings in water sales were estimated at 17.2; 6.7 and US$8.6M/y for the RO, EDR and GYP-CIX processes, respectively (worst case). Therefore, the operational costs of the EDR and GYP-CIX processes are the lowest if the sale of water is taken into consideration. This may favour the EDR and GYP-CIX processes for the desalination of the mine water.