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Solar wastewater treatment (SOWAT) was the subject of experiment between April and September using low cost and mastery equipment: ‘hot-box’ stills. Using a separate still, treated wastewater (i.e. distillate) production was recorded between 2.4 and 6 l m−2 day−1. Treatment efficiency was comparable to the activated sludge treatment process. Biological oxygen demand (BOD) recorded between 86 and 90% of abatement. Raw wastewater turbidity was reduced by 99%, from 181 nephelometric turbidity units (NTU) to 1.6 NTU. The treatment also allowed wastewater disinfection. The inactivation of total coliforms, faecal coliforms and faecal streptococci was estimated at about 99%. SOWAT offers the advantage of grouping, in a separate piece of equipment, three steps of conventional wastewater treatment: (i) the pre-treatment, (ii) the biological and (iii) disinfection treatments. Also, this sustainable treatment does not consume electricity and consequently does not emit greenhouse gases (GHGs). Used on a medium and large scale, SOWAT would be promising for safe wastewater reuse in agriculture. This could secure food production of poor and low-income countries, especially those that are very sunny. Copyright © 2017 John Wiley & Sons, Ltd.

Nowadays, water availability and quality represent a major challenge. In 2050, the United Nations Organization predicts that 44% of the world population will face severe water scarcity. Countries located in sub-humid and semi-arid regions of the world will be especially concerned for this problem, because of their low supply of rainwater. The aim of this study is to suggest the disinfection treatment by irradiation as a complement wastewater treatment to obtain a safe microbial quality of water and permit its reuse. This last is limited to 1.000 CFU/100 ml (i.e. equivalent to 3 log) of fecal coliforms by the Algerian and WHO standards. The experiments were conducted to disinfect wastewater by UVA, UVC, and solar radiation. The UVA and UVC disinfection treatments were carried out using an experimental bench composed of three flat-bottom flasks and three Erlenmeyers of 2 L each. The solar disinfection treatment was experimented using a 30 L-tubular photoreactor in a stationary and a dynamic flow. Th...

Wastewater treatment sector, in Algeria, uses exclusively two processes: the activated sludge applied in the north and the lagooning in the highlands and the south. In the operating balance of the National Sanitation Office (ONA), the activated sludge wastewater treatment plants are characterized by a high electricity consumption which induced high cost and greenhouse gas (GHG) emission. In 2010, about 104.32 million m3 of wastewater was treated. This operation consumed 30,900 MWh of electricity which cost 1.04 million Euros (€) and emitted 18,761 tons of CO2-equivalent. In 2013, the treated wastewater increased by 35.2% and the electricity consumption by 45.8%. To establish an exhaustive diagnostic, this study evaluated the electricity consumed during 2009/2010 in an activated sludge wastewater treatment plant of 70,000 population equivalents (PE) (i.e. Unit of a pollution load produced daily per person, fixed at 60 grams of DBO5, which is used for the sizing of the wastewater treatment plants). ...

The wastewater reuse, especially for irrigation, requires a safer microbial quality. However, the tertiary treatment is often nonexistent, especially in developing countries where, unfortunately, wastewater treatment needs to be more systematic. Solar water disinfection processes could be appropriate treatments for improving the microbial quality of the wastewater reuse. This study evaluates the effectiveness of both solar photolysis and solar photocatalysis processes in disinfecting secondary-treated wastewater recovered from an activated sludge wastewater treatment plant where the disinfection treatment is not applied. The best parameters of the solar disinfection processes were determined. The experiments were conducted in a bench test composed of 4 flat-bottom flasks with a volume of 2 L each. Then, the disinfection efficiency of both processes was evaluated by a comparative study where 250 Wh/m2 of UV radiation was cumulated. The disinfection efficiency of studied pathogenic (1) total colifor...

In Algeria, the activated sludge processes and the aerated lagoons and are mainly applied to treat wastewater. Worldwide, these treatment processes are recognized for their high electricity consumption and significant sewage sludge production. So, to reduce the electricity consumption, the management of the wastewater treatment plants had integrated the sewage sludge electricity generation. Recently, the sludge conditioning by solar energy is also widely applied.