Evaluating alternatives

Once you have narrowed down your design to a few workable concepts, it is customary to use an evaluation table similar to the one shown in Table 3.3 to evaluate alternative concepts in more detail. You start by assigning a level of importance (I) to each design criterion. For example, you may use a scale of 1 to 5, with 1=1 indicating little importance, and 1 = 5 signifying extremely important. Next you will rate (R) each workable concept in terms of hew well it meets each design criterion. You may use a scale of R = 3 for high, R = 2 and R = 1 for medium and low, respectively. 

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Often more than one synthetic route may be available to prepare a particular com pound Indeed it is normal to find m the chemical literature that the same compound has been synthesized m a number of different ways As we proceed through the text and develop a larger inventory of functional group transformations our ability to evaluate alternative synthetic plans will increase In most cases the best synthetic plan is the one with the fewest steps... 

Properties of Solid Wastes Information on the properties of solid wastes is important in evaluating alternative equipment needs, systems, and management programs and plans. 

Chemical Composition Information on the chemical composition of sohd wastes is important in evaluating alternative processing and recoveiy options. If solid wastes are to be used as fuel, the four most important properties to be known are ... 

Define a produet and programme quality requirements Evaluate alternative suppliers Seleet suppliers... 

Evaluate alternatives for protecting the facilities from events that can result in plant freezeup... 

Evaluate alternatives to upgrade the raw water system valve bos and piping... 

J 5 Use formal charge calculations to evaluate alternative Lewis structures (Toolbox 2.2 and Examples 2.6 and 2.8). 

However, the significance of results from such analyses depends on the quality of the input data. For example, laboratory recipes often do not meticulously document solvent and auxiliary input masses. In many cases, water inputs and waste management are not determined before the pilot stage is reached. Estimates similar to those applied in LCA may be used in order to complete a preliminary mass balance. While such estimations cause considerable uncertainty, it seems more appropriate to evaluate alternatives based on preliminary information, that is, experience-based assumptions concerning the production of substrate or catalyst, than to simply ignore potentially important contributions to the mass balance. 

The need to evaluate alternatives often arises once the decision to eliminate chemicals of concern is made. Sometimes a chemical of concern can be eliminated through product design such as through the use of a material that is inherently flame retardant or a fabric barrier without the need for added flame-retardant chemicals. But when the only currently feasible option appears to be a chemical substitution, then the alternatives must be evaluated and assessed to ensure that they are in fact greener than the chemical they are intended to replace. We provide as examples of implementing alternatives assessment, the Green Screen for Safer Chemicals and the DfE Flame Retardants in Printed Circuit Boards Partnership. 

In many cases, various risk-reduction alternatives will result in a tolerable level of risk. Cost-benefit analysis can be a useful tool in evaluating alternative approaches. Costs are generally straightforward and easy to estimate however, estimating benefits may be more difficult, requiring assumptions that allow all benefits to be expressed using a common basis, usually monetary. 

The components of FS comprise developing, screening, and evaluating alternative remedial actions. 

U.S. EPA, How to Evaluate Alternative Cleanup Technologies for Underground Storage Tank Sites A Guide for Corrective Action Plan Reviewers, EPA 510-R-04-002, U.S. EPA, Washington, 2004. 

Within the project we also evaluated alternative methods as tools to obtain information on the toxicological and physicochemical profile of the pollutants. In this paragraph, an example of the application of QSARs models is reported a comparison is done between predicted values from different models or between QSARs evaluation and experimental values from internationally recognized databases. 

Gomberg, A. Buchbinder, B. Offensend, F.J. Evaluating Alternative Strategies for Reducing Residential Fire Loss - The Fire Loss Model, NBSIR 82-2551, National Bureau of Standards, Gaithersburg, MD, 1982. 

The QRA method is designed to provide managers with a tool to help them evaluate the overall risk of a process. QRAs are used to evaluate potential risks when qualitative methods cannot provide an adequate understanding of the risks. QRA is especially effective for evaluating alternative risk reduction strategies. 

If asymptotic conditions occur before cleanup standards are reached, the operator should evaluate alternative procedures that will complete the remediation, or consider renegotiation with the lead agency regarding more reasonable cleanup... 

One critical issue is the evaluation alternative. In the case of methanolysis, the alternatives are to make DMT and EG by depolymerization or secure materials from traditional petrochemical sources. For hydrolysis, the alternatives are TPA and EG by depolymerization or from traditional sources. For both technologies, the amount of copolymerizing isophthalate and/or 1,4-cyclohexane dimethanol is likely to be too little to justify the cost of recovery. For the various forms of glycolysis and the methanolysis/BHET hybrid, the alternative is the BHET and BHET-like materials made by the combination of a terephthalate and isophthalate plus EG and various glycols. Market prices exist for TPA and EG. BHET is not an item of commerce, and so the value must be imputed from the market price for TPA (the modern terephthaloyl) and EG, plus a conversion cost. 

ICCVAM has evaluated alternative test methods for acute oral toxicity, genetic toxicity, biologies, immunotoxicity, dermal corrosion and irritation, ocular toxicity, developmental toxicity, pyrogeni-city, and endocrine disrupter effects (ICCVAM 2007). As examples, alternative test systems for dermal corrosion and irritation are described in the following text. 

Challenge baseline premises, and purposely seek out and evaluate alternatives and opportunities. 

A research and advocacy organization that evaluates alternative policies and programs, particularly those at the state level, in order to reduce prescription drug prices and increase access to medications. 

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