The treatment of dairy factory waste water by coagulation and decantation has shown that calcium hydroxide at a weak dose of 0.49–0.63 g provides the highly efficient removal of suspended matter (SM) (94%) and total phosphorus (Tp‐P) (89%) accompanied by an average elimination of chemical oxygen demand (COD), total Kjeldahl nitrogen (TKN‐N), faecal coliforms (FC) and faecal streptococci (FS). This is within the Moroccan limits for the first two parameters (SM and TP‐P). The dose necessary to obtain optimal removal is 0.8–1.2 g when using aluminium sulfate and 0.6–0.75 g with iron chloride and the percentage elimination of chemical and bacteriological pollutants is not substantial. However, coagulation by calcium hydroxide induced less sludge (0.93 g/L) than either aluminium sulfate (1.21 g/L) or iron chloride (1.38 g/L). In terms of cost, the price of treating 1 m3 of dairy effluent by using calcium hydroxide is lower (approximately 25 times less expensive) than when using the other two coagulants.

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-Dairy effluent characterization and treatment by coagulation-decantation.The qualitative and quantitative characterization of an effluent produced by a dairy plant located in the Doukkala region (Morocco) for one year showed that this plant consumed on average 632 m 3 /day of drinkable water, of which 85% was rejected as wastewater. This dairy effluent is overloaded with organic matter: [average chemical oxygen demand (COD): 6140 mg·L -1 ± 10%], total Kjeldahl nitrogen (average TKN-N: 148 mg·L -1 ± 10%), total phosphorus (average TP-P: 29 mg·L -1 ± 10%), fecal coliforms (average FC: 2.33 × 10 4 CFU·mL -1 ± 10%) and fecal streptococci (average FS: 4.00 × 10 4 CFU·mL -1 ± 10%). These parameters go beyond the limit values fixed by the Moroccan project of norms relative to rejected liquids, which shows the necessity of treating this polluted liquid before releasing it into the natural environment. The treatment of this effluent, which consists of coagulation-decantation by iron chloride [FeCl 3 , is insufficient for the removal of organic matter and nitrogen (the percentage of elimination does not surpass 40%). However, this treatment considerably reduced the suspended matter (94%) and total phosphorus (89%) with calcium hydroxide. Consequently, it respected the Moroccan standards for these two latter parameters. In order to suggest a more efficient treatment, this chemico-physical treatment may serve as a stage of pretreatment and it would then be necessary to proceed to a complementary biological process. Dairy effluent / characterization / pollution / coagulation-decantationRésumé -La caractérisation physico-chimique et bactériologique de l'effluent global brut rejeté par une industrie laitière située dans la région des Doukkala (Maroc) a révélé que ce rejet liquide est très chargé en matière organique exprimée en terme de demande chimique en oxygène (DCO moyenne : 6140 mg·L -1 ± 10 %), en azote total Kjeldahl (N-NTK moyen : 148 mg·L -1 ± 10 %), en phosphore total (P-PT moyen : 29 mg·L -1 ± 10 %), en coliformes fécaux (CF moyenne : 2,33 × 10 4 UFC·mL -1 ± 10 %) et en streptocoques fécaux (SF moyenne : 4,00 × 10 4 UFC·mL -1 ± 10 %). Le traitement de cet effluent par coagulation-décantation à l'aide du chlorure ferrique, du sulfate d'aluminium et de la chaux, quoique insuffisant vis-à-vis de l'élimination de la pollution organique et azotée, dont le taux d'abattement optimal ne dépasse guère 40 %, a permis de réduire considérablement la matière en suspension (94 %) et le phosphore total (89 %) par la chaux et par conséquent de respecter les normes marocaines en vigueur pour ces deux paramètres. Dans le but de suggérer un traitement qui soit plus efficace, la coagulation-décantation peut servir comme une étape de prétraitement. Il serait donc nécessaire de procéder à un traitement biologique complémentaire.Effluent laitier / caractérisation / pollution / coagulation-décantation * Auteur correspondant : ahamdani@caramail.com 318 A. Hamdani et al.

In order to study the simultaneous removal of nitrate and organic matter from a dairy effluent containing 670 mg∙L-1 of nitrate (NO3--N) and 5 760 mg∙L-1 of dissolved chemical oxygen demand (CODd), denitrification in a laboratory scale bioreactor consisting of an immersed bacterial bed colonized by an heterotrophic denitrifying flora (HDF) selected for NO3- reduction, COD consumption and adapted to grow on an effluent produced by a dairy industry was investigated. The obtained results indicated that at the optimal conditions of temperature (30°C), pH (7), COD/NO3--N ratio (5), the operation lasted 108h with total reduction of nitrate in 72h, no nitrite accumulation, and 92% of soluble COD removal in 96h. This indicates that the biodenitrification was accompanied with a high efficiency of matter organic removal as an electron donor, and thereby satisfies the applicable standards.

Introduction Seismic data acquisition using ocean-bottom cable (OBC) methods, whilst capturing valuable azimuthal information, often presents challenges in the signal processing sequence for successful removal of unwanted noise and multiples-related energy. Herein, we present the results of methods that have enhanced the standard noise and multiple attenuation workflows. We present results on linear noise and shear-wave removal utilizing wavelet scale decompositions to complement tau-p transforms, receiver and source line interpolations using a "beyond-aliasing" approach for improved multiple model prediction and also subsequent imaging, and wavefield extrapolation to sea level plus adaptive subtraction for long-period multiples removal. Whilst it is always desirable to acquire data with uniform and dense coverage, acquiring 3D OBC wide-azimuth surveys can be challenging and expensive due to limits imposed by operational complexity and safety, time scheduling due to weather windows and environmental considerations, in-situ infrastructure and obstructions, and others. This typically results in compromises to surface acquisition grid sampling, i.e., large source and/or receiver line spacing. To mitigate the sparseness of OBC acquisition, an innovative and cost-effective staggered-grid source-receiver survey design was implemented, with the goal of improving spatial sampling without incurring the need for more equipment or increased operational complexity (Chandola et al., 2014). In this work, we show the effect of the surface grid on seismic processing and imaging and illustrate seismic data processing techniques to improve surface coverage further to overcome the acquisition limitations efficiently. Survey Geometry The survey geometry was oriented north-south for receiver lines, and east-west for source lines. The nominal spacing between receiver lines was 300 m and 250 m for source lines, whilst the receiver interval was 50 m and the source point interval was 25 m. Water depths within the survey area ranged from 8 m to 50 m (Figure 1). An innovative staggered grid source plus receiver layout was implemented within the development area. The goal was to increase spatial subsurface sampling from 12.5- x 25-m bins within the exploration areas, to 12.5 m x 12.5 m within the developmental areas without incurring additional acquisition cost. This staggered design was coupled with denser source line spacing in the developmental area to improve the coverage fold and near-offset distribution.