Rinse model implementation of alkaline detergent in clean‐in‐place process with gradual flow reduction for economy of water and effluent reduction

Abstract Demand for water savings in clean‐in‐place (CIP) process has increased due to the limited offer of this natural resource. Thus, this work investigated the CIP with variable flow in the rinse step in a stainless steel piping system contaminated with alkaline detergent residues compared to CIP with constant flow for rinse water (RW) saving purposes. In addition, the dynamics of the conductivity of the effluent of the CIP system, typically found in dairies, was investigated and water consumption estimated. For this purpose, a CIP prototype was used, which was subjected to cleaning with alkaline detergent (NaOH) at 70°C for 15 min and later rinsed, evaluating the flow reduction effect. The removal of alkaline residue was evaluated under steady state and variable conditions using computer simulation in software Matlab™/Simulink™. The dynamics of alkaline residue removal was modeled using the first order transfer function with dead time (FOPDT) and the gradual flow reduction strategy for rinsing was predicted using the interpolation of the models. The results showed that both strategies were significant for the residues of detergent removal. However, the reduction in spent RW volume was more significant for the variable flow, representing 35% of potable water savings compared to the conventional process with constant flow, what suggests an interesting strategy to reduce the environmental impact caused by the CIP process. Finally, the FOPDT models were effective in predicting the rinse dynamics and determining the time of the process. Practical applications Strategies to reduce rinse water consumption and to guarantee food safety are essential. Variable rinse flow can be used in dairy industries to improve economy of water and energy during rinse stage of a CIP process in comparison with the time spent considering the stationary flow process, commonly employed in dairy. In addition, this change is attractive, as it can be made with only adjustments to the control system, not necessarily requiring new equipment.