PICTOU, N.S. — The picturesque harbour town of Pictou, N.S., has had an uneasy relationship with its job-rich, toxin-spewing neighbour almost since it opened in 1967. Now, the Northern Pulp mill is facing a possibly existential challenge over the massive amounts of effluent it casts off each day. After years of pumping 70 million litres of treated wastewater a day into lagoons on the edge of the Pictou Landing First Nation reserve, Northern Pulp wants to pipe it into the near