[The problems of sanitary safety of environment in the USSR during the first five-year plans period in 1930s]

The article briefly considers the history of solving problems of sanitary environmental protection in the USSR during the first five-year plans in 1930s. The numerous examples from the Fund of the all-Union state sanitary inspection in the State archive of the Russian Federation were involved into consideration of issues of conservation of water in open reservoirs and air quality in cities. The conclusion is made about the inability of sanitary organization to implement assigned tasks of environmental safety due to disregarding of these issues by authorities, lacking of necessary legislative basis, subordinated position of sanitary services and deficiency of funds and manpower.

Safe surface concept in vertical flow constructed wetland design to mitigate infection hazard

Decentralized wastewater management based on vertical flow constructed wetlands (VFCWs) can be an effective solution for minimizing sanitation problems also in urban landscapes, especially when considering rapidly expanding cities in developing countries. Yet, the mass implementation of VFCWs in urbanized areas first needs improvement of a few design drawbacks - among them, the control of infection hazard is of primary importance. Therefore, in this study, the possibility of mitigation of the VFCW-derived infection hazard was assessed, through analysis of bacteriostatic properties of top filtration layer materials, according to clinical experiences based on "safe" antimicrobial surfaces. The experiment was carried out on a daily operating VFCW. Coliform bacteria survival rates were measured for known VFCW construction materials such as Pinus bark, gravel, slag, charcoal and LECA. The calculated die-off rates expressed as 12-h first-order inactivation coefficients ranged between 6.91 h^-1 (slag/summer) and 0.58 h^-1 (Pinus bark/autumn). The obtained die-off curves showed charcoal, Pinus bark and LECA to have little bacteriostatic properties - even occasionally providing conditions promoting the growth of the coliform population. Meanwhile, slag and gravel were strictly inhibiting bacteria growth, reducing the population up to 99% within the first 3 h of contact time. The research showed that it is possible to significantly mitigate the infection hazard of VFCW by means of proper top-layer substrate material, similar or equal to slag or gravel.