MERRILLVILLE, Ind. (AP) -- Removing ammonia and other pollutants from wastewater before it reaches the treatment plant at BP PLC's oil refinery in Whiting is likely the best option for keeping pollution from reaching Lake Michigan, scientists said Thursday.

Scientists from Purdue University Calumet's Water Institute and Illinois' Argonne National Laboratory presented options BP can use to treat polluted water that will be a byproduct of processing heavy Canadian crude oil at its refinery just east of Chicago. BP is spending $3.8 billion so the refinery can increase production of motor fuels by about 15 percent.

Among the technologies the scientists looked at was using membranes to remove suspended solids — tiny particles that elude some treatment methods — from the water as well as methods for removing salt and other debris. They also looked at using heat to remove ammonia, and using biological systems to remove both ammonia and suspended solids from the water.

BP officials promised last year to reduce the amount of ammonia and suspended solids it discharges into Lake Michigan after environmentalists and Illinois politicians protested the Indiana Department of Environmental Management's decision to allow BP to increase its discharges.

The findings presented to about 60 community members on Thursday were a preliminary report. George Nnanna, the water institute's interim director, said the scientists will give a report to BP by the end of the month.

'The final findings will be of tremendous value to BP as it conducts its review of water treatment options for this project,' BP spokesman Scott Dean said. 'Based on the preliminary report, their findings appear to be very promising.'

Nnanna said he hopes the report will be used by other facilities, both industrial and municipal, that discharge into Lake Michigan to help reduce pollution.

After presenting their final report to BP later this month, the scientists plan to work on looking at ways to reduce discharges of mercury and other metals into Lake Michigan and take a look at other sources of pollution in the lake.