Assessment and optimization of the oxygen based membrane biofilm reactor as a novel technology for source-diverted greywater treatment.

The oxygen based membrane biofilm (O2-MBfR) has been proved to be a novel technology in treating greywater (GW) and response surface methodology (RSM) was used to model the removal of chemical oxygen demand (COD) and total nitrogen (TN) with operation parameters COD/TN ratio, system pH and lumen air pressure (LAP). Results indicated that the all target single factors affect GW treatment efficiency, and the regression model with central composite design (CCD) showed good agreement with the experimental results with high R2 and R2 adj values (all >0.97) for all the target responses. Statistical evaluation revealed that system pH was the most significant parameter affecting COD and TN removal, followed by COD/TN ratio and LAP. The interaction between COD/TN ratio and system pH also played an important role on the GW treatment. The optimized maximum removal of COD (96.48%) and TN (133 g N/m2-day) were achieved with the COD/TN ratio 17.76 g COD/g TN, system pH 7.10 and LAP 1.00 psi. Thus, RSM combined with CCD could be used for predicting the organics and nitrogen removal during GW treatment in the O2-MBfR.

Methods for Assessing and Optimizing Solar Orientation by Non-Planar Sensor Arrays.

Non-planar sensor arrays are used to determine solar orientation based on the orientation matrix formed by orientation vectors of the sensor planes. Solar panels or existing photodiodes can be directly used without increasing the size or mass of the spacecraft. However, a limiting factor for the improvement of the accuracy of orientation lies with the lack of an assessment-based approach. A formulation was developed for the supremum (i.e., the least upper bound) of orientation error of an arbitrary orientation matrix in terms of its influencing factors. The new formulation offers a way to evaluate the supremum of orientation error considering interference with finite energy and interference with infinite energy but finite average energy. For a given non-planar sensor array, a sub-matrix of the full orientation matrix would reach the optimal accuracy of orientation if its supremum of orientation error is the least. Principles for designing an optimal sensor array relate to the configuration of the orientation matrix, which can be pre-determined for a given number of sensors. Simulations and field experiment tested and validated the methods, showing that our sensor array optimization method outperforms the existing methods, while providing a way of assessment and optimization.