Technological Options for Safe Resource Recovery from Fecal Sludge

Finding cheap and sustainable ways to improve soil fertility continues to be a major detriment to improving agricultural productivity of many small and medium farms. For the most part, farmers in developing countries apply animal  manure  and farm residues or have to pay for chemical fertilizers to improve soil fertility. Unfortunately, in many cases such animal manure is not readily available and chemical fertilizers are expensive and not always available or appropriate to specific conditions.

This is not the case for human manure which is mostly readily available, and this in large amounts, especially in  urban  and  peri-urban  areas. The organic matter and nutrients contained in excreta can be recovered and recycled as fertilizer-cum-soil conditioner – an effect not shared by chemical fertilizers – that is direly needed in tropical soils.

However, its use is being constrained in some areas due to technical challenges for safe use, the bulky nature if composted, and social challenges which include negative perceptions of using human excreta in agriculture.

Over the last ten years, researchers from IWMI have identified a number of options for safe resource recovery from Fecal Sludge. The options provide the stages and technical solutions available for safe recycling of  Fecal Sludge  and  its  by-products,  mainly  in  agriculture.

In two Resource Recovery and Reuse reports the following technical options are covered:

  • Options to recover nutrient rich solids from liquid fecal sludge. This includes thickening systems and dewatering systems and how to adjust the moisture and content.
  • Processes for liquid effluent treatment such as waste stabilization ponds and constructed wetlands.
  • Treatment process such as composting and co-composting, and compost pelletization.

As composts can be bulky and cumbersome to transport, store and apply, IWMI is pelletizing the compost. This is not only reducing the volume of the product and improving compost handling, but also allows to blend (enrich) the pellets with additional nutrients the specific crop or soil needs. This tailor-made organic-mineral fertilizer is one of the innovations IWMI’s RRR team offers and for which it is testing the market and different business models in various countries. As the excreta pellets recover up to half of the nutrients in fecal sludge collected from on-site sanitation systems, the solution is strongly promoting nutrient cycling.

Technological options for safe resource recovery from fecal sludge

Nikiema, J.; Cofie, O.; Impraim, R. 2014. Technological options for safe resource recovery from fecal sludge. Colombo, Sri Lanka: International Water Management Institute (IWMI). CGIAR Research Program on Water, Land and Ecosystems (WLE). 47p. (Resource Recovery and Reuse Series 2). doi: 10.5337/2014.228