Nomograms as a graphical model to predict biogas at municipal wastewater treatment plant using fuzzy indices

Abstract

The strength of municipal wastewater and sludge considering their potential for biogasification can be expressed in terms of multiple parameter comprehensive indices (MPCI), namely, Wastewater Comprehensive Index (WWCI) and Sludge Comprehensive Index (SCI), respectively. Both of these indices can be calculated using fuzzy multiple criteria decisions making (FMCDM). Simple linear equations are established to express the relation between these indices, suspended solids concentration and biogas. The linear equation is developed to predict biogas from multiple parameter comprehensive indices, which indicate the linear relation between strength of wastewater, sludge and biogas. Nomogram was developed to get immediate quantification of biogas by linear scaling of suspended solid concentration and multiple parameter comprehensive indices (MPCI). Using a linear equation obtained from regression analysis; a suitable scale was developed to construct the nomogram. The biogas was found 96% precise with reference to measured one when estimated using nomograms. A single parameter, that is, suspended solids concentration will be monitored at municipal wastewater treatment plant, by digital device; to save chemicals, time, power and human resource. While taking efforts toward smart cities; digitalization and resource conservation will be creditable.