ABSTRACT: In waste materials, proximate analysis measuring the total
concentration of carbohydrate, protein, and lipid contents from solid wastes
is challenging, as a result of the heterogeneous and solid nature of wastes.
This paper presents a new procedure that was developed to estimate such
complex chemical composition of the waste using conventional practical
measurements, such as chemical oxygen demand (COD) and total organic
carbon. The procedure is based on mass balance of macronutrient elements
(carbon, hydrogen, nitrogen, oxygen, and phosphorus [CHNOP]) (i.e.,
elemental continuity), in addition to the balance of COD and charge intensity
that are applied in mathematical modeling of biological processes. Knowing
the composition of such a complex substrate is crucial to study solid waste
anaerobic degradation. The procedure was formulated to generate the
detailed input required for the International Water Association (London,
United Kingdom) Anaerobic Digestion Model number 1 (IWA-ADM1). The
complex particulate composition estimated by the procedure was validated
with several types of food wastes and animal manures. To make proximate
analysis feasible for validation, the wastes were classified into 19 types to
allow accurate extraction and proximate analysis. The estimated carbohydrates,
proteins, lipids, and inerts concentrations were highly correlated to
the proximate analysis; correlation coefficients were 0.94, 0.88, 0.99, and
0.96, respectively. For most of the wastes, carbohydrate was the highest
fraction and was estimated accurately by the procedure over an extended
range with high linearity. For wastes that are rich in protein and fiber, the
procedure was even more consistent compared with the proximate analysis.
The new procedure can be used for waste characterization in solid waste
treatment design and optimization. Water Environ. Res., 81, 407 (2009).