A review of the existing solids management practices in Trinidad and Tobago and experience elsewhere defined the future needs and identified solar drying as a preferred technology for the subject project. Upon analysis of the local conditions, it was calculated that approximately 19 MJ/m 2 (1886 kWh/m²) of solar radiation, at 30ºC annual average temperature and 80% relative humidity level is appropriate at the project site and that these parameters are adequate for the solar dryer application. The estimated 7,450 m 2 cell area for drying associated with average electrical power consumption of 18 to 20 kWh/tonne of water extracted will provide an evaporation rate of 2.2 kg water/m 2 .day. The solids are expected to be dried from approximately 16-18% dry solids to 70-90% dry solids.

The City of Winnipeg has been evaluating options for its new water treatment plant's (WTP's) residuals management. Several mechanical systems such as centrifugation and belt presses were reviewed. However, a cost effective and environmentally friendly solution was desired for final dewatering of the solids sludge. Due to the favourable climatic conditions, the feasibility of freeze thaw technology for the City of Winnipeg's residuals solids dewatering was evaluated. A desktop evaluation and pilot study were completed. The desktop study concluded that freeze thaw ponds have been effectively used throughout cold regions of Canada and the United States. Due to the large scale of the Winnipeg project and to obtain practical confidence in the technology, a pilot scale sludge thickening test device was constructed in order to more closely identify the anticipated sludge concentration and supernatant quality after thickening. From a ten-week pilot trial, it was noted that solids concentrations increased from approximately 0.6% by weight to as high as 8% by weight after freezing. The test results also showed that the sludge solids concentration as high as approximately 50% can be achieved with an adequate drying period. Conventional higher energy technologies do not provide such a high solids concentration. Upon review of the pilot work and desktop study, the application of the freeze thaw technology was accepted as the way forward for the City of Winnipeg solids dewatering project. Due to site constraints, operational and economic reasons, the design of the facility posed several challenges. This paper intends to highlight some of the design criteria and challenges.

Recently, more stringent nutrient effluent limits have been imposed by the Province of Manitoba to protect Lake Winnipeg. These limits include restricting the amount of total nitrogen to less than 15 mg/L and total phosphorus to less than 1 mg/L. Achieving concentration based effluent limits on high strength wastewaters present unique challenges not encountered with municipal wastewaters. For example, municipal wastewaters typically contain about 40 mg/L of nitrogen in the influent and therefore have to remove approximately 65% of nitrogen to meet the new 15 mg/L effluent limit. However, influent nitrogen concentrations in meat processing wastewaters are about 250 mg/L, requiring over 95% removal to meet the same limit. This also applies to the phosphorus content where municipal influents typically contain about 5 mg/L while meat processing wastes contain around 25 mg/L. The purpose of this paper is to describe a fast track approach taken to complete the preliminary design, detailed design and construction a large expansion within a one year period to become Manitoba's first treatment facility to meet the Province's new nutrient effluent limits. In addition, the first 16 months of operating data is provided highlighting some of the challenges of commissioning a new treatment facility and meeting concentration based limits with a high strength wastewater.