Three last forms of water pollution exist in the forms of petroleum, radioactive substances, and heat. Petroleum often pollutes waterbodies in the form of oil, resulting from oil spills. The previously mentioned Exxon Valdez is an example of this type of water pollution. These large-scale accidental discharges of petroleum are an important cause of pollution along shore lines. Besides the supertankers, off-shore drilling operations contribute a large share of pollution. One estimate is that one ton of oil is spilled for every million tons of oil transported. This is equal to about 0.0001 percent. Radioactive substances are produced in the form of waste from nuclear power plants, and from the industrial, medical, and scientific use of radioactive materials. Specific forms of waste are uranium and thorium mining and refining. The last form of water pollution is heat. Heat is a pollutant because increased temperatures result in the deaths of many aquatic organisms. These decreases in temperatures are caused when a discharge of cooling water by factories and power plants occurs.
The major sources of water pollution can be classified as municipal, industrial, and agricultural. Municipal water pollution consists of waste water from homes and commercial establishments. For many years, the main goal of treating municipal wastewater was simply to reduce its content of suspended solids, oxygen-demanding materials, dissolved inorganic compounds, and harmful bacteria. In recent years, however, more stress has been placed on improving means of disposal of the solid residues from the municipal treatment processes. The basic methods of treating municipal wastewater fall into three stages: primary treatment, including grit removal, screening, grinding, and sedimentation; secondary treatment, which entails oxidation of dissolved organic matter by means of using biologically active sludge, which is then filtered off; and tertiary treatment, in which advanced biological methods of nitrogen removal and chemical and physical methods such as granular filtration and activated carbon absorption are employed. The handling and disposal of solid residues can account for 25 to 50 percent of the capital and operational costs of a treatment plant. The characteristics of industrial waste waters can differ considerably both within and among industries. The impact of industrial discharges depends not only on their collective characteristics, such as biochemical oxygen demand and the amount of suspended solids, but also on their content of specific inorganic and organic substances. Three options are available in controlling industrial wastewater. Control can take place at the point of generation in the plant; wastewater can be pretreated for discharge to municipal treatment sources; or wastewater can be treated completely at the plant and either reused or discharged directly into receiving waters.
水污染可分为市政，工业和农业。市政供水污染包括废水家园和商业机构。多年来，主要目标是处理城市 废水只是减少其内容的悬浮固体，氧要求的材料，溶解无机化合物和有害细菌。近年来，但是，更多的压力放在了改善的手段处置固体残留物由市政处理过程。基本方法的城市污水处理分为三个阶段：初级治疗，包括砂砾清除，筛选，粉碎，和沉淀;二级处理，这需要氧化溶解有机质的手段，利用生物活性污泥，然后驶离和处理，其中先进的生物脱氮方法和化学和物理方法，如颗粒过滤和活性炭吸收就业。处理和处置固体残渣可以 至百分之五十的资本开支和运营成本的污水处理厂。特征的工业废水可以相差很大内部和国家之间产业。影响工业排放不仅取决于其集体特征，如生化需氧量和悬浮固体量，而且还对它们的内容具体的无机和有机物质。.三个选项可在控制工业废水。管制可以在点的代工厂;废水预处理可以出院市政治疗来源;或废水处理完全可以在工厂，或者重复使用或直接排放到接收水域。