- Sewage sludge--Congresses (6)
- Animal waste--Congresses (2)
- Agricultural wastes--Congresses (1)
- Organic compounds--Environmental aspects--Congresses (1)
- Organic wastes--Congresses (1)
- Phosphorus--Environmental aspects--Congresses (1)
- Sewage--Congresses (1)
- Sewage--Purification--Congresses (1)
- Soil pollution--Congresses (1)
- Soils--Phosphorus content--Congresses (1)