All

The Council of Ministers issued a Royal decree number M/6 1421 H, corresponding to 2000 AD. The decree stated that, in Saudi Arabia, all wastewater should be treated at the tertiary level, without any discrimination (in terms of the type of reuse and discharge locations). The aim of this article is to discuss and elaborate the royal decree (2000AD), showing its limitations and recommending several modifications. This paper is a review and analysis of treated wastewater reuse in Kingdom of Saudi Arabia (KSA) and impact of implementation of royal decree for the treatment of wastewater reuse in future. Moreover, a critical appraisal of the use of tertiary treatment was done by elaborating negative impact of tertiary treatment and comparing a review of treatment of wastewater reuse in USA.  It is emphasized in the paper that degrees of wastewater treatment should depend on: (a) types of reuses/discharges, methods of irrigation and local environmental conditions, and (b) whether irrigation takes place in restricted or unrestricted agriculture and types of crops. Thus, the Saudi Royal Decree (2000AD) that requires wastewater treatment up to a tertiary level needs to be re-evaluated and modified. The article suggested correlating the degree of wastewater treatment with the intended reuse, discharge locations and the degree of exposure to the public. 

The present study is carried out to explain the presence of large concentrations of SO₂ in atmosphere of Pakistan during June, 2011. Large volcanic eruptions are a major source of greenhouse and trace gases. The eruption of Mount Nabro in June, 2011 injected large amount of SO₂ into stratosphere. Nabro volcanic eruption generated a layer of sulfate aerosols, which resided in stratosphere for months. The total amount of SO₂ that was injected into the atmosphere was estimated to be 1.3-2.0 Tg. Data products of Global Ozone Monitoring Experiment (GOME-2), Ozone Monitoring Instrument (OMI) and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) were used to study SO₂ concentrations and plume movement over Pakistan. HYSPLIT backward trajectory model is utilized to study the origin of SO₂ plume. The study confirms that SO₂ plume originated from Nabro volcanic eruption and caused significant atmospheric perturbations and affected the air quality of Pakistan. SO₂ emissions from volcanic eruptions can pose serious hazard to population as well as global climate.

This study compares the distinctive performance, yield and characteristics of bioflocculants (UPMBF13) derived from submerged (SmF) and solid-state fermentation (SSF) of Bacillus subtilis UPMB13. The bioflocculants were subjected to morphological characterization, functional groups determination, molecular weight measurement, protein content quantification and specific compound identification. The SmF and the SSF strategies yielded an average of 2.70 g l^-1 and 1.25 g kg^-1 of UPMBF13, respectively. The submerged UPMBF13 resulted in a clear suspension with visible flocs formation, while flocs from the SSF treatment were less apparent. Higher total proteinaceous contents of UPMBF13 from the SSF led to the inferiority in flocculating performances. The produced UPMBF13 consisted of hydroxyl, carboxyl, methoxyl and carbonyl functional groups which contributed to their flocculating abilities. The molecular weights of UPMBF13 were around 10-50 kDa, characterizing them into low-molecular weight bioflocculants. The submerged UPMBF13 were more fibrous in nature than the SSF, giving the submerged UPMBF13 the upper hand in flocculation. SmF was the best fermentation method yielding high performing bioflocculants at a faster rate by the utilization of non-elaborative techniques. SSF, on the other hand, was proven feasible but further improvements are needed. 

The growing number of polluted land areas makes the question of rehabilitation and safe/effective use of these areas increasingly imperative. For land polluted by heavy metals, the possibility of transferring the toxic pollutants to humans through the food chain further increases the importance of the safe management of polluted lands.  We examined the possibility of using heavy metal-polluted areas for growing specific aromatic plants, which can be used either as food herbs/infusions, or to produce high value products. In a pot experiment, chamomile, sage and thyme plants were exposed to a range of concentrations of Cd, Pb, and Ni in the soil. Toxic metal levels were determined in the roots, leaves and flowers (for chamomile) of the plants. All three plants accumulated relatively high amounts of metals in their roots, whereas the aboveground parts exhibited lower accumulation capacity. Regardless the levels of metal accumulation, the quality of essential oils from chamomile, sage, and thyme was not affected and in all cases the extracted essential oils were free of heavy metals. Our results suggest that the aromatic plants under study cannot be consumed either as food additives or as infusions. However, under strict control of the cultivations, heavy metal-contaminated areas can be used for the production of essential oils from aromatic plants.