wastes 528 recycling of wastes 226 waste disposal services 200 house-hold wastes 75 environment 65 industrial wastes 61 treatment 61 more ... environment protection 52 biological wastes 45 secondary raw materials 40 toxic waste 37 composts 33 waste incinerators 33 sorting 32 storage of wastes 31 environmental pollution 31 agricultural wastes 28 biofuels 27 dumps 24 legal regulations 23 hazardous wastes 20 provisions 20 unconventional energy sources 19 synthetic polymers 19 radioactivity 18 combustion 17 health harmful substances 17 waste water treatment 16 ecology 15 civil engineering 14 less ...