Heterotrophic bacteria eat most of the carbon-based materials in raw sewage while autotrophic bacteria consume ammonia and nitrogen compounds.
异养细菌可以吃掉未处理污水当中的大部分碳基物质；而自养细菌则会消耗掉氨氮化合物。
Another important group of petrochemical raw materials are the aromatic compounds, principally benzene, toluene and xylenes, which are mainly produced by catalytic reforming.
另一组重要的石油化学品原料是芳香烃化合物，主要是苯、甲苯和二甲苯，主要由催化重整制得。
Substances that have been manufactured by chemical means using petroleum compounds or natural gas as raw materials.
以石油化合物或天然气为原料用化学方法制造的物质。
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