Added-value from linking the value chains of wastewater treatment, crop production and bioenergy production: A case study on reusing wastewater and sludge in crop production in Braunschweig (Germany)

The limited availability of natural water resources and dependency on mineral fertilizer challenge agricultural value chains in arid and nutrient-poor areas. Reusing wastewater in agriculture may help and could reduce costs and lead to increased added-value. The objective of this analysis is to assess the economic impact of linking the value chains of wastewater treatment, crop production and the generation of bioenergy by reusing treated municipal wastewater and sludge. The assessment was based on the cost/benefits and the added-value from the reused wastewater by the Braunschweig Wastewater Association (Germany). Benefits were assessed by comparing the costs of wastewater irrigation and sludge application with conventional disposal options, as well as comparing the costs of irrigation and fertilization with treated wastewater to groundwater irrigation and mineral fertilization. The added-value was calculated by ascertaining the remunerations received by the stakeholders in the various value chains. The results indicate that the reuse of wastewater and sludge results in: (a) the development of linked regional value chains; (b) lower costs of wastewater treatment and sludge disposal; (c) higher profitability and added-value in crop production; and (d) a high share (77%) of regional added-value. However, the results also show that the reuse of wastewater and sludge within linked value-chains can restrict actors and lead to crowding out effects on the added-value. Agricultural reuse schemes should provide additional opportunities that enable farmers to increase their scope of possibilities and compensate for missed economic potential.