A phytoplankton study found high nutrient concentrations linked to sewage effluents. One study found 10 different antibiotics in sewage treatment effluents, surface water, and sediments. However, there have been environmental problems with untreated corrosive effluents or accidental discharges. Both rivers are heavily polluted with effluents and trash from domestic and commercial sources. Many industrial effluents contain toxic metals that must be removed. Additionally, environmental pollution can be diminished through removal of nutrients from effluents. The manufacture of paper usually requires inorganic chemicals and creates water effluents. This eliminates hazardous solvents from the production environment, and from factory effluents. He deduced that the ventricles contained cerebrospinal fluid which collected waste products from effluents. Over 200 firefighters were exposed to toxic smoke and effluents during the firefighting efforts. Over 90 different compounds were identified in combustion effluents from polystyrene. The value of the original organisms grown on human waste effluents was minimal. It means the control of emissions and effluents into air, water or soil. Three farms grow seaweeds for feed in abalone effluents in land-based tanks. There are similar problems with industrial effluents.