Recent studies have reported that sewage sludge increases crop yields by 10 to 85% compared to common fertilizers, so its use can generate great benefits in the agricultural sector.
Sewage sludge or biosolids are organic materials produced during wastewater treatment through biodegradation, which can be used for various beneficial purposes, such as incorporation into soils or soil to supply it with nutrients and to renew organic matter. Sewage sludge can be used on agricultural land, forests, grazing fields, or disturbed land in need of reclamation.
The disposal of sewage sludge through land application has several purposes and environmental benefits:
- Organic matter improves soil characteristics (such as texture and water absorption) for optimal plant growth.
- It provides more favorable conditions for root growth and increases vegetation tolerance to drought.
- Provide essential nutrients for plant growth, including nitrogen and phosphorus, as well as some essential micronutrients, such as nickel, zinc and copper.
- They also serve as an alternative or substitutes or supplements to chemical fertilizers.
- The nutrients contained in biosolids are not as soluble as those in chemical fertilizers, and are therefore released more slowly.
- Sewage sludge is a recycled product, so its application does not reduce the amount of any non-renewable resources, such as phosphorus.
- Despite the multiple benefits it could have for crops, in Mexico, sewage sludge management is a neglected aspect and few wastewater treatment plants have a sludge treatment system.
With all the waste sludge generated from daily activities, it is necessary to promote cleaner production processes among the agricultural and industrial sectors that minimize the generation of waste sludge, the recovery of reusable material from it, and avoid discharging untreated wastewater to the drainage network.
It is also extremely important to involve the population in the efficient use of water and cleaning products (detergents, disinfectants, solvents, etc.), which are sometimes used excessively, causing problems in wastewater treatment plants due to the formation of foams and the destabilization of biological treatment systems.
The objective of proper sewage sludge management is to solve pollution problems and convert a waste product into a usable and non-hazardous resource to be reused without sanitary risk. To achieve this, it is essential that agricultural and food industries have a treatment plant in their facilities capable of removing the pollutants present in the wastewater, which can even be reused for agricultural irrigation, and that allow the final disposal of the sewage sludge to be incorporated into their crop fields.