Toxicologie environnementale et analytique

Magnesium ammonium phosphate hexahydrate (MgNH₄PO₄.6H₂O), commonly known as struvite is a crystalline mineral of low solubility. In wastewater treatment facilities, separating phosphorus by conversion to struvite could reduce its content in the wastewater. The experiment conducted for local wastewater sources to identify better source and recover struvite for phosphatic fertilizer evaluation. Chemical precipitation through pH elevation and (Mg²⁺:NH₄⁺-N:PO₄^3--P) molar ratio were used to recover NH₄⁺ and PO₄^3- as struvite from sewerage water of different sites. To recover (MAP) magnesium ammonium phosphate hexahydrate from the four different sources, chemicals including MgCl₂.6H₂O+Na₃PO₄ were applied at molar ratio (Mg²⁺:NH₄⁺-N:PO₄^3-P=1.2:1:1) and at different pH ranging from 8.0 to 11.0. Results indicated that maximum P removal was obtained as 87% at pH 10.5 from the source of I-9 sector containing high levels of P. For N results indicated that maximum N removal was obtained as 67% at pH 10.0 from the same source of P removal. In the experiment among various combinations, comprising of Mg:N:P ratio, pH levels and stirring speeds, the stirring speed of 250 rpm for 30 minutes was more desireable for struvite precipitation process. The MAP precipitation significantly reduced the contents of NH₄⁺ and PO₄^3- in sewerage water at different sites. So, it is necessary to develop the optimum conditions for small-scale and commercial production of struvite, because struvite recovery is technically feasible and economically beneficial. Therefore, this technology provides opportunities to recover phosphorus sustainably from sewerage water and preserve phosphorus reserves.

The aim of this paper was to verify the effectiveness of environmental management and protection measures and to improve the efficiency of ecological construction and protection on the Loess Plateau in China. The unit area ecosystem service value (ESV) equivalent factor for land use categories was dynamically revised by using data such as farmland grain yield, net primary production (NPP), and rainfall. A dynamic evaluation model of the Loess Plateau ecosystem service value was established to evaluate the ESV as well as spatial and temporal dynamic evolution characteristics. From 1990 to 2015, the dynamic degree of ecological land in the study area was 8.867%. Apart from paddy fields, dry land, and deserts, the transfer rates showed an increasing trend. Bare land was converted into other land use types at an increasing rate, while forest areas increased slowly and cultivated areas first increased and then decreased. Grassland areas only slightly decreased, while wetland and water areas remained relatively stable. From 1990 to 2015, the ESV fluctuated largely, albeit with an overall improvement. The ecosystem service value showed an obvious spatial heterogeneity, with higher values in the south compared to the north of the Loess Plateau.

Introduction: Charcoal is a residue that occurs from the results of decomposition of wood due to heat when most of the chemical components are carbon. One method of making wood charcoal is to use a stove. Charcoal is an important factor in determining the sustainability of the lives of surrounding communities that have long been running. Therefore, the purpose of this study is to create a strategy based on the SWOT analysis to see if the charcoal business using mangrove forests can proceed or not.

Materials and methods: Analysis of sustainable development strategies using SWOT Analysis which is one of the analyses used to formulate a strategy in an area of development. This analysis consists of 4 basic elements, namely strengths, weaknesses, opportunities and threats. These four elements come from two main factors: internal factors (strengths and weaknesses) and external factors (opportunities and threats). While the stages in the SWOT analysis.

Results: Analysis of public perception of the existence of charcoal trading business in the Bengkalis District gave a “Good response” with a score of 2.66. These results illustrate that the existence of a charcoal trading business does not provide a bad impact as long as it is in a location around a mangrove forest. The results obtained in the SWOT matrix diagram are in the fourth quadrant, show that the priority of the strategy is the Strength (S) and Threats (T) strategies. The components in these two strategies need to get more emphasis and attention so that the existence of a charcoal trading business can be sustainable. Conclusion: The public perception of the charcoal long-standing regulation in the” Bengkalis Regency” is in the “Good category” which is a prerequisite in the development of continuous charcoal. The strategy for sustainable charcoal development is in quadrant IV, namely the S-T strategy.

Njoro River, which is the primary freshwater source for the urban and rural-based residents within its basin, has been subjected to increasing anthropogenic pressure that threatens its ecological and socio-economic values. An empirical study was conducted in the mid reaches of this river to determine the effect of organic effluents on water quality and benthic macroinvertebrate community structure. Organic pollutants input into the river can lead to immense ecosystem impairment. The effect of organic effluents on water quality was assessed in this study using a combination of physico-chemical parameters and benthic macroinvertebrate community structure. Four sampling sites were chosen corresponding to both diffuse and point source pollution of organic effluents. Dissolved oxygen, conductivity, turbidity and pH were determined in situ. Water samples were collected using 500 ml acid washed bottles before laboratory analysis for Biological Oxygen Demand, nitrogen, phosphates and Total Suspended Solids. Benthic macroinvertebrates were sampled using a kick net (mesh size 250 μm with an effective area 0.2025 m2) during each sampling session and identified using aquatic invertebrates identification keys. Results indicate that effects of organic effluents were more pronounced at downstream sites compared to the upstream ones. One-Way ANOVA indicated a significant difference in dissolved oxygen, conductivity, Biological Oxygen Demand, turbidity, ammonium, nitrates and total phosphorus levels among the sampling sites. Benthic macroinvertebrates species diversity was high in upstream sites with order Ephemeroptera being the most dominant taxa (51.26%) whereas order diptera dominated the downstream sites (42.38%). Among the genus of order diptera identified downstream, genus Polypedilum was dominant. The results from this study form baseline information in biomonitoring the Njoro River which can be adopted at a wider scope to the existing management strategies and policies towards pollution control and abatement in aquatic systems.