Waste conversion, other method

The simplest method for producing sodium phosphates involves the neutralization of phosphoric acid with either sodium hydroxide or carbonate, but, unless some waste source of alkali is found, it may not be the most economical. For this reason other methods of producing sodium phosphates were investigated. The two most promising methods involve conversion of monocalcium phosphate (or normal or triple superphosphate fertilizer) to sodium phosphate by ion exchange, and neutralization of phosphoric acid with dilute sodium hydroxide produced electrolytically from brine. 

The valorization of by-products in biomass conversion is a key factor for introducing a biomass based energy and chemistry. There is the need to develop new (catalytic) solutions for the utilization of plant and biomass fractions that are residual after the production of bioethanol and other biofuels or production chains. Valorization, retreatment or disposal of co-products and wastes from a biorefinery is also an important consideration in the overall bioreftnery system, because, for example, the production of waste water will be much larger than in oil-based refineries. A typical oil-based refinery treats about 25 000 t d-1 and produces about 15 000 t d 1 of waste water. The relative amount of waste water may increase by a factor 10 or more, depending on the type of feed and production, in a biorefinery. Evidently, new solutions are needed, including improved catalytic methods to eliminate some of the toxic chemicals present in the waste water (e.g., phenols). 

Waste waters containing low concentrations of soluble organic lead in the presence of high concentrations of other diverse ions such as Cl pose a particularly difficult treatment problem. Generally, organic lead exists in solution as the tri- or dialkyl lead chloride species. These salts are not amenable to the conventional methods used to remove inorganic lead, viz., those of pH adjustment followed by settling. The technique of chemical conversion of the... 

Transmaterialisation is a more fundamental approach to the problem, which, with the goal of sustainable development, would ultimately switch consumption to only those resources that are renewable on a short timescale. Clearly petroleum, which takes millions of years to form, is not an example of such a sustainable resource. For the method to be truly effective, the wastes associated with the conversion and consumption of such resources must also be environmentally compatible on a short timescale. The use of polyolefin plastic bags for example, which have lifetimes in the environment of hundreds of years, is not consistent with this (no matter how they compare with alternative packaging materials at other stages in their lifecycle), nor is the use of some hazardous process auxiliaries which are likely to cause rapid environmental damage on release into the environment. 

Incineration is a well-known process that involves the conversion of toxic and hazardous waste into a less or nontoxic waste by heating at a very high temperature to convert them into gaseous and particulate matter. Incineration is considered an attractive option after source reduction, and recycling. This method is sometimes preferred over the other treatment methods because it destroys permanently the hazardous components in the waste material. 

However, a tabulation of properties of typical WCF calcine incorporated by various post treatment methods is given in Table VII (13), Also shown are the properties of the untreated WCF calcine. In some instances the numerical values of the property vary by several orders of magnitude, while in others only qualitative terms are used. The term retrievability is very important and can mean either a simple recovery (e.g., as from the WCF storage bins) in preparation for packaging and shipping to a repository, or recovery and use or conversion to another form. For example, if one converts a calcined waste to a glass or ceramic block, the unit may be easily retrievable for shipment but may be very difficult to process to another form or to recover specified fission products. On the other hand, untreated WCF calcine has had a minimum of treatment, can be converted to any other form, can be readily processed for desired components, and is fully retrievable. 

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