Extraction of extracellular polymers from activated sludge using a cation exchange resin

The carbonization of biomass residuals to char has strong potential to become an environmentally sound conversion process for the production of a wide variety of products. In addition to its traditional use for the production of charcoal and other energy vectors, pyrolysis can produce products for environmental, catalytic, electronic and agricultural applications. As an alternative to dry pyrolysis, the wet pyrolysis process, also known as hydrothermal carbonization, opens up the field of potential feedstocks for char production to a range of nontraditional renewable and plentiful wet agricultural residues and municipal wastes. Its chemistry offers huge potential to influence product characteristics on demand, and produce designer carbon materials. Future uses of these hydrochars may range from innovative materials to soil amelioration, nutrient conservation via intelligent waste stream management and the increase of carbon stock in degraded soils.

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Hydrothermal carbonization of biomass residuals: a comparative review of the chemistry, processes and applications of wet and dry pyrolysis

The enzymatic activity of activated sludge was investigated with special emphasis on the localization of the enzymes in the sludge floc matrix. Activated sludge from an advanced activated-sludge treatment plant, performing biological N and P removal, was used. An enzymatic fingerprint was established using a panel of six different enzymes. The fingerprint revealed peptidase as the most dominating specific enzyme tested. By monitoring sludge bulk enzymatic activity over a 3-month period using fluorescein diacetate as an enzyme substrate, considerable variations in activity were observed even over short periods (a few days). The variation in esterase activity was to some extent correlated to the presence of humic compounds in the sludge, but not to the sludge protein content. Comparison of full sludge enzyme activity to the activity of a batch-grown sludge culture indicated that enzymes accumulated in sludge flocs. A large proportion of the exoenzymes were immobilized in the sludge by adsorption in the extracellular polymeric substances (EPS) matrix. This was demonstrated by extraction of EPS from the activated sludge using cation exchange. Contemporary to the release of EPS a very large fraction of the exoenzymes was released into the water. This showed that the exoenzymes should be considered to be an integrated part of the EPS matrix rather than as direct indicators of the microbial activity or biomass.

Enzymatic activity in the activated-sludge floc matrix

http://www.medecine-maritime.fr/pdf/biblio/toxico/Environmental%20levels,%20toxicity%20and%20human%20exposure%20to%20tributyltin.pdf

Environmental levels, toxicity and human exposure to tributyltin (TBT)-contaminated marine environment. A review

A comparative study of the nature of biopolymers extracted from anaerobic and activated sludges

The fate of tributyltin in the aquatic environment

Formation and conditional stability constants of complexes formed between heavy metals and bacterial extracellular polymers

Characterisation of metal forms in sewage sludge by chemical extraction and progressive acidification

Methods of deflocculating activated sludge to facilitate separation of extracellular material have been investigated. Total sludge carbohydrate was estimated to be 160 mg g−1 SS, of which 60 mg g−1 SS could be extracellular. An alkaline treatment extracted this quantity but a less rigorous ion-exchange technique was chosen for routine extraction.

Robert M. Sterritt

Papers

The fate of tributyltin in the aquatic environment

Formation and conditional stability constants of complexes formed between heavy metals and bacterial extracellular polymers

Characterisation of metal forms in sewage sludge by chemical extraction and progressive acidification

Extraction of extracellular polymers from activated sludge

Metal removal by adsorption and precipitation in the activated sludge process