Slurry dewatering and conversion of biosolids to a renewable fuel

摘要

In the processes for treating municipal sewage and storm water containing biosolids to discharge standards, biosolids, even after dewatering, contain typically about 80% water bound in the dead cells of the biosolids, which gives biosolids a negative heating value. It can be incinerated only at the expense of purchased fuel. Biosolids are heated to a temperature at which their cell structure is destroyed and, preferably, at which carbon dioxide is split off to lower the oxygen content of the biosolids. The resulting char is not hydrophilic, and it can be efficiently dewatered and/or dried and is a viable renewable fuel. This renewable fuel can be supplemented by also charging conventional biomass (yard and crop waste, etc.) in the same or in parallel facilities. Similarly, non-renewable hydrophilic fuels can be so processed in conjunction with the processing of biosolids to further augment the energy supply.

主权项

1. A process of converting biomass into a renewable fuel comprising the steps of:
providing biomass comprising at least about 10% water; applying sufficient pressure to the biomass to maintain liquidity and form pressurized biomass; heating the pressurized biomass to a first temperature, wherein the first temperature is sufficient to form an aqueous biomass char slurry, carbon dioxide, and free water; depressurizing the biomass char slurry; separating the carbon dioxide from the biomass char slurry; removing at least a portion of the free water from the biomass char slurry to provide a dewatered biomass char product containing a decreased oxygen content; and utilizing the dewatered biomass char product as a fertilizer.