COD and nutrient removal from urban effluent by desmodesmus subspicatus

O trabalho teve como objetivos avaliar o crescimento heterotrófico e potencial de remoção de DQO e nutrientes (nitrogênio e fósforo) da microalga clorofícea Desmodesmus subspicatus em esgoto doméstico coletado em estação piloto de tratamento e reúso de água do CCA/UFSCar. Os resultados indicaram velocidades específicas de crescimento máximas de 0,084 h????1, com concentrações de biomassa de 1000 mg L????1 em 24 horas de cultivo. Devido à composição do efluente esterilizado, tanto a quantidade de matéria orgânica como nitrogênio são limitantes para o crescimento microbiano. Entretanto, para valores de DQO acima de 200 mg L????1, houve uma elevada conversão de matéria orgânica do efluente em biomassa. Estes resultados sugerem a viabilidade de aplicação desta microalga para produção de biomassa e remoção de parte dos nutrientes e matéria orgânica deste efluente, podendo ser considerada como uma das etapas de adequação para reúso agrícola de esgoto doméstico.

MUTAGENESIS IN Tradescantia pallida AS A BIOMARKER OF THE EFFECTS OF WATER POLLUTED WITH URBAN EFFLUENT

The present paper evaluated the toxicity of effluent released into the Tiete River, in Barra Bonita City, São Paulo State, using the test micronucleus with Tradescantia pallida. Young inflorescences of T. pallida (n = 20) were partially immersed in one of three treatments: water containing effluent, a positive control (0.1% formaldehyde), and a negative control (distilled water). The results showed a statistically significant difference (p < 0.05) between groups, indicating the genotoxicity of the effluent.

Decoupling dependence on natural water: reflexivity in the regulation and allocation of water in Israel

Since 1999, Israel has secured a decoupling between the total water supplied and water derived from the natural environment through surface and groundwater. Between 2007 and 2010, this decoupling enabled a cut of over 20% in natural water use, while maintaining overall supply volumes despite drought. By 2009–2010, natural water supply had been reduced to the levels of the early 1960s. As seawater desalination contributed less than 10% to the total supply up to 2009, decoupling was achieved primarily through cross-sector efficiency and the recycling of urban effluent. This study uses the case of Israel to exemplify the challenges faced by semi-arid economies in achieving a gap between the upward trend in total national water use and local water withdrawn from natural resources. Decoupling will be shown to comprise two types. One type occurs when an economy ceases to be water self-sufficient. Another type is encountered when an economy has the capacity to remedy its over-exploitation of natural water. It will be shown that the first decoupling is non-contentious and non-politicised. The investments and reforms needed to bring about the second decoupling appear very demanding economically and very politically stressful.