Zero Effluent Stretch Target (zest)

"The goals of this project were to assess the viability of avoiding water use and of “cascading” water uses, i.e. using outlet water from one process in another activity, possibly with some purification, including the upgrading of the final effluent stream for internal reuse. Water use has been inventoried at FMC Biopolymer, Cork. Avoidance and reduction measures were identified that could reduce water consumption from 49m /hr to 19 m /hr (a reduction in excess of 60%), with an annual saving in excess of €350,000. These projects were assessed for feasibility and implementation. Potential streams that could be subject to extensive recovery have been examined and potential technologies have been investigated. Process Water Recycling Projects A number of process water recycling projects have been implemented on completion of this thesis. Water usage has decreased by 30% since the beginning of this project, as a consequence of process water recycling projects and greater awareness of the importance of water usage on site. The projects that have been fully implemented are • Niro Scrubber Water Recycle • Niro Atomiser Cooling Water Recycle, • Bowen Atomiser Cooling Water Recycle, • and Water Balance. The following projects will be implemented by the final quarter of 2006, bringing further reductions; • Bowen Scrubber Water Recycle • Ammonia Drum Project • And Improved control of pump seal water Membrane Water Recycling Project Two streams were identified as presenting significant potential for reuse, if the streams can be purified to the required specifications: the solids separator stream and the effluent plant outfall stream. As part of this research the recycling of the solids separator stream was piloted on site using membrane technology. The specific technology piloted was ultrafiltration followed by double pass reverse osmosis. Due to the low pH of the stream, a pH adjustment step was also included to increase the pH. The pilot plant was fed with the actual process stream, accepting the normal production variations, to better test the tolerance to plant variability. The results achieved from the pilot plant to date are encouraging with the membranes removing 98.5% of the COD and almost 100% of the remaining critical parameters, which are turbidity, suspended solids, conductivity and dissolved solids. No micro-organisms were present in the final permeate stream either. Further piloting of this stream is required to achieve greater COD reduction before moving onto the Outfall stream. However, when piloting is completed and if the project goes to full scale, it will reduce FMC’s water bill by 37% (Solid Separator) or 50% (outfall), depending of which stream FMC choose. (These percentages are excluding the process water recycling projects)."