I am happy to announce that Issue 23 of Sustainable Sanitation Practice (ISSN 2308-5797) on "Green walls/roofs" is available and can be downloaded, free of charge now from www.ecosan.at/ssp/

Various aspects are covered in the four papers presented in this issue:
• Fabio Masi and co-workers present case studies from Italy, India and Tanzania,
• Andrea Zraunig et al. present VertECO, a vertical ecosystem for greywater treatment,
• Manfred Radke and Andrea Zraunig report on green walls for humidification of rooms, and
• Ulrike Pintha and Bernhard Scharf summarize the requirements and challenges in the interdisciplinary planning process needed to implement such technologies.

With best regards,
Guenter Langergraber
Editor SSP journal