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The main purpose of this study resides essentially in the development of a new tool to quantify the biomass in the bioreactor operating under steady state conditions.

Modeling is the most relevant tool for understanding the functioning of some complex processes such as biological wastewater treatment. A steady state model equation of activated sludge model 1 (ASM1) was developed, especially for autotrophic biomass (XBA) and for oxygen uptake rate (OUR). Furthermore, a respirometric measurement, under steady state and endogenous conditions, was used as a new tool for quantifying the viable biomass concentration in the bioreactor.

The developed steady state equations simplified the sensitivity analysis and allowed the autotrophic biomass (XBA) quantification. Indeed, the XBA concentration was approximately 212 mg COD/L and 454 mgCOD/L for SRT, equal to 20 and 40 d, respectively. Under the steady state condition, monitoring of endogenous OUR permitted biomass quantification in the bioreactor. Comparing XBA obtained by the steady state equation and respirometric tool indicated a percentage deviation of about 3 to 13%. Modeling bioreactor using GPS-X showed an excellent agreement between simulation and experimental measurements concerning the XBA evolution.

These results confirmed the importance of respirometric measurements as a simple and available tool for quantifying biomass.

The aim of this paper is to better understand the good news coming from Africa and reflect on ideas discussed at the “Africa 2060: Good News from Africa” conference in April 2010 organized by Boston University's Frederick S. Pardee Center for the Study of the Longer‐Range Future.

Africa's performance over the last 50 years has been akin to a roller coaster ride of good news followed by bad news, with the bad news dominating. However since the dawn of the millennium Africa's outlook has increasingly become optimistic. As one looks at Africa's future, several questions emerge: which of these gains can be consolidated? Which of the positive trends will be sustained? Has this recent period of global attention provided the continent with a real institutional scaffolding on which a positive future can be built? And what needs to be done to ensure that the dangers of chronic poverty, conflict, and institutional collapse that still lurk in the shadows will be contained long enough that they eventually disappear?

The authors base their observations on the intense discussions during the conference by practitioners and experts and an engaged and informed audience, plus a broader reading of the literature, including that which was presented at the conference. These observations reflect a locus of expert and informed opinion and provide a window into the priorities that are engaging the imaginations of those thinking deep and hard about Africa's future. The authors distill seven key drivers that are of particular importance in shaping Africa's longer‐range future. Of course, all of these can operate in either a positive or a negative direction. It is the decisions that will be made by African and international policy‐makers, businesses, civic organizations, and citizens today that will determine which direction Africa will be “driven” towards tomorrow.

There are a number of exciting opportunities that await Africa in its future, but many of these also come with potential hurdles and pitfalls. Innovation, entrepreneurship, technology, knowledge, and globalization are among the areas that have generated significant good news to record from Africa. But within each of these areas there is also the potential and reality of bad news. The choice now lies with African citizens, decision makers and societies as to whether they are able to make the type of decisions that will control the negative tendencies of these drivers and accelerate the positive tendencies.