The preparation of synthetic sludge for lab testing

Abstract

For carrying out sludge lab-scale tests, and interlaboratory trials for standards validation, the availability of samples with "certified and constant" characteristics is required. When "dried sludge" samples cannot be used, problems arise because (i) most fresh sludge characteristics change with storage time, also because some preservation practices are not applicable or their effects unknown, (ii) some fresh sludge characteristics are strongly affected by handling, and (iii) fresh sludge requires particular precautions and authorization for transportation. This means that using "fresh sludge" samples cannot guarantee reliability and reproducibility of results, so a valid alternative consists in testing "synthetic suspensions" samples to be on-site prepared. This should also give the possibility to compare results obtained in different places and times. Within this framework, Task Group 3 (TG3) of Working Group 1 (WG1) of Technical Committee 308 (TC308) of European Standardization Committee (CEN) undertook the preparation of a Technical Report dealing with the preparation of synthetic suspensions, both inorganic and organic, in repeatable conditions, able to describe the behaviour of a real sludge. This paper discusses a proposal for ingredients and modalities to prepare such synthetic suspensions that will be systematically tested in already planned lab experiments to define an optimal recipe.

Partitioning of Viruses in Wastewater Systems and Potential for Aerosolization

“…We considered both types of sludge to balance a well-defined composition of the fluid against real-world conditions. For synthetic sludge, we followed a published recipe 25 with the following modifications. We adjusted the solid content to match that of our actual sludge.…”

Impact of Sludge Floc Size and Water Composition on Dewaterability

“…The use of synthetic waters minimizes differences in experimental conditions, which is particularly important for most laboratory-scale tests [19]. The properties of 'natural' or 'real' water samples can often be highly variable and very dynamic.…”

“…The properties of 'natural' or 'real' water samples can often be highly variable and very dynamic. These properties depend on the operational conditions of the treatment plant and may change over time during transport, handling, and storage [19]. Although the water and sludge compositions impact on the sludge characteristics, there has been no detailed investigation of the effects of different water compositions on the sludge floc size and on the dewaterability of the associated sludge.…”

“…In contrast, domestic wastewater is relatively high in organic content such as human feces [17,18]. Furthermore, organic sludge contains fats, fibers, protein, and sugars [19].…”

A new polystyrene-latex-based and EPS-containing synthetic sludge

“…Synthetic sludge is a chemical surrogate that behaves like activated sludge in certain aspects like dewatering, settling and conditioning characteristics, while shows much higher robustness and stability to variable operating conditions [12]. Several studies have been conducted to find appropriate materials for preparation of various types of synthetic sludge and to explore their applications [12][13][14][15].…”