Using the water pinch analysis to optimize the water network of a brewery and its neighbours to achieve circularity

Abstract

Water is an important resource in many industries in the world. Due to emerging regulatory framework, change in consumer’s perspective and increasing costs for water, industries are forced to move towards sustainable water use. Nowadays, improvements in the brewery industry are focussed on increasing the efficiency of the processes or treating the complete wastewater stream on site. Water network optimization models can effectively decrease the fresh water flowrate and wastewater flowrate production. The water pinch is in most cases used to optimize fresh water use and wastewater production in a single industry. This thesis is the first to use the water pinch in a circularity concept of a wider network with a brewery and external user. Circularity is in this thesis defined as the percentage of water from a brewery that can be reused by an external party, after it has been used inside the brewery. Two case breweries in Egypt were used to illustrate the water pinch method, El Obour brewery and Sharkia brewery. For both breweries an orange orchard of 87 ha with a water demand of 9836 m3/month was indicated as the external user. Per brewery, a list of water using processes that produce an effluent was determined. This list contains the CIP processes in the brew house and cellars and includes every process in the packaging department. In addition, the utility department processes cooling towers, boilers and CO2 washers were part of the water network of the breweries. The initial water network of El Obour consisted of 18 brewery processes and one external user, the orange orchard. Sharkia brewery had 17 brewery processes and the orange orchard. Actual process water flowrates were used as well as UBM process water flowrates. For El Obour brewery the initial fresh water flowrate was 9755 m3/month and 8466 m3/month for UBM process water flowrates. The Sharkia brewery initial fresh water flowrate was 15695 m3/month and 14961 m3/month for UBM process water flowrates. COD, Total N and Na+ were identified as key constituents. Per key constituent, a composite curve was constructed and a new, optimized water network designed. For the El Obour brewery the water pinch steps were described in detail to show how the composite curves and the networks could be constructed. The Sharkia brewery was used to validate the method. With the composite curve and pinch point determined, processes could be indicated as source or sink. The orange orchard was always considered as a sink and was satisfied first with every possible source. The water that was flowing from the brewery to the orange orchard identified the circularity potential of the network. COD was the reference constituent for both breweries as the most restrictions occurred in this network. With the COD limiting network as basis, integrated networks were designed that complied with every constituent restriction. The results showed that for El Obour the fresh water consumption decreased with 7% to 7909 m3/month and the wastewater production decreased with 22% to 6607 m3/month. Resulting in an initial circularity potential of the El Obour brewery of 11 – 13% (depending on the used process water flowrates based on actual measurements or UBM). The fresh water consumption and wastewater production savings for Sharkia were respectively 0% and 34%. The Sharkia brewery could be 28 – 34% circular on water in the initial phase without treatment of effluents (depending on the used process water flowrates based on actual measurements or UBM). 100% circularity could not be achieved due to too high Na+ and COD concentrations. Total N caused no restrictions for reuse. The results show that the water pinch can be used to determine to what extend the case breweries can be circular on water with an external user. The water pinch is not only an optimization tool but it can help industrial sites including a brewery to identify collaboration between different users of the local watershed. Hereby increasing the circularity on water.