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Several studies have focused on improving the properties of soil blocks/bricks due to perceived and real strength and durability limitations. A review of 56 published studies is presented on the effect of stabilization on the performance characteristics of soil blocks. The review found that few studies have been conducted on durability properties of enhanced soil blocks as compared with physico-mechanical properties. Fibre-enhanced soil blocks tended to have peak performance with an optimal content that achieved maximum performance. The maximum performance improvement was generally less than a doubling of the strength of the soil without the fibres. Binders showed a continual improvement with greater concentrations, so much greater improvements can be obtained if the economic and social costs can be justified. Both fibres and binders have variable performance on water absorption with both reductions and increases possible. Generally, both fibre and binder inclusion in soil blocks enhance the performance characteristics of the blocks. Binders are typically more effective on a mass-fraction basis.However the supply of fibres is usually at a lower cost and a reduced environmental impact, and therefore may have a better performance on a per-cost or per-impact basis.

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-Chromium is a pollutant present in tannery wastewater, its removal is necessary for protection of the environment. Penisetum purpureum, Brancharia decumbens and Phragmites australis were grown hydroponically in experimental gravel beds to determine their potential for the phytoremediation of solutions containing 10 and 20 mg Cr dm . These concentrations, similar to tannery wastewater after initial physicochemical treatment were used with the aim of developing an economic secondary treatment to protect the environment. All the systems achieved removal efficiencies of 97 -99.6% within 24 hours. P. purpureum and B. decumbens removed 78.1% and 68.5% respectively within the first hour. Both P. purpureum and B. decumbens were tolerant of the concentrations of chromium applied, but P. purpureum showed the greatest potential because its faster growth and larger biomass achieved a much greater chromium removal over the whole length of time of the experiment.