Water reuse from wastewater: Experiences and challenges of implementing a full-scale water reuse system in a food industry plant

Abstract

This paper presents experiences and challenges related to the implementation and successful 3-year operation of a full-scale station for water reuse from wastewater in one of the largest poultry slaughterhouses in Europe. Solved problems for implementing deammonification, as well as automatic coagulant dosing for wastewater pre-treatment, improvement of activated sludge separation, and digestate management, are presented and discussed. Two major limitations of stable water reclamation were a limit of 30 mg N/L in the effluent to the river and the passing of cationic flocculants and natural polymers formed by activated sludge microorganisms to the ultrafiltration units. The limit of 30 mg N/L was achieved by implementing i) a unique deammonification system to treat leachate from the anaerobic digester, ii) automatic coagulant dosing to mitigate high nitrogen peaks and balance organic compounds between biogas production and efficient denitrification. Flocculants and polymers passing to the ultrafiltration units and causing a sharp drop in water recovery were eliminated by stabilizing the zeta potential of the sludge, adding an antiscalant before the ultrafiltration, and automatic control of wastewater coagulation at primary treatment, responding to COD peaks. With improvements described in the article, the water reuse system provides a stable supply of 4000 m3/d of high-quality water, resulting in over 4 million m3 of water reclaimed since 2020.