Two things are needed for any technology to be suitable for use in the industry, viz.1.Technical feasibility and 2. Economical feasibility. The use of ultrasound for waste water treatment has been shown to be technically feasible by numerous reports in the literature over the years. But there are hardly any exhaustive reports which address the issue of economical feasibility of the use of ultrasound for waste water treatment on industrial scale.

Hence an attempt was made to estimate the cost for the waste water treatment using ultrasound. The costs have been calculated for 1000 lit/min capacity treatment plant. The costs were calculated based upon the rate constants for phenol degradation. The time required for ninety percent degradation of phenol was taken as the residence time. The amount of energy required to achieve the target conversion was calculated from the energy density (watt/ml) used in the treatability study. The cost of treatment was estimated by considering capital cost and operating cost involved for the waste water treatment. Quotations were invited from the vendors to estimate the capital cost of equipments involved, and operating costs were calculated based on annual energy usage. The cost is expressed in dollars per 1000 gallons of waste water treated. The cost has been estimated for phenol, TCE and azo-dye as model pollutants. These treatment costs are compared with other established AOP technologies. The cost of waste water treatment for phenol was in the range of $89 per 1000 gallons for UV/US/O3 to $15527 per 1000 gallons for US alone. These costs for TCE were in the range of $25 per 1000 gallons to $ 91 for US+UV treatment. The cost of waste water treatment for reactive dyes was in the range of $56 per 1000 gallon for US+UV+H2O2 to $2367 per 1000 gallon for US alone. Where possible, these estimated treatment costs are compared with AOP costs reported in the technical literature.

This study will help in quantifying the economics of waste water treatment using ultrasound on industrial scale. We strongly believe that this study will immensely help the researchers working in the area of applications of ultrasound for waste water treatment in terms of where the technology stands today as compared to other available commercial AOP technologies. This will also help them identify, for different ways to improve the efficiency of using ultrasound or search for other ways of generating cavitation which may be more efficient and help reduce the cost of treatment in the future.