Cultivation of Chlorella pyrenoidosa in outdoor open raceway pond using domestic wastewater as medium in arid desert region.

Chlorella pyrenoidosa was cultivated in secondary wastewater effluent to assess its nutrient removal capabilities. Wastewaters were obtained from a wastewater treatment plant located in Ouargla, Algeria. The experiments were conducted in winter under natural sunlight in an outdoor open raceway pond situated in the desert area. The highest biomass of the microalgae was found to be 1.71±0.04g/L. Temperatures ranged between 18 and 31°C. The average annual insolation was no less than 3500h with an annual solar irradiance of more than 2000kWh/m(2). Analyses of different parameters including COD, NH4(+)-N and TP were conducted throughout the cultivation period. Their average removal efficiencies were 78%, 95% and 81% respectively. The results demonstrated the potential of nutrient removal by microalgae grown on secondary wastewater in arid areas.

1,3-Diallyl-6-bromo-1H-imidazo[4,5-b]pyridin-2(3H)-one.

In the mol-ecule of the title compound, C(12)H(12)BrN(3)O, the fused-ring system is essentially planar, the largest deviation from the mean plane being 0.0148 (3) Å. The two allyl groups are nearly perpendicular to the imidazo[4,5-b]pyridine plane [C-C-N-C torsion angles of 81.6 (4) and -77.2 (4)°] and point in the same direction. The planes through the atoms forming each allyl group are nearly perpendicular to the imidazo[4,5-b]pyridin-2-one system, as indicated by the dihedral angles between them of 80.8 (5) and 73.6 (5)°.

3-Allyl-6-bromo-1H-imidazo[4,5-b]pyridin-2(3H)-one.

In the mol-ecule of the title compound, C(9)H(8)BrN(3)O, the fused-ring system is almost planar, the largest deviation from the mean plane being 0.008 (3) Å. The plane through the atoms forming the allyl group is roughly perpendicular to the imidazo[4,5-b]pyridin-2-one system, as indicated by the dihedral angle between them of 70.28 (11)°. In the crystal, each mol-ecule is linked to its symmetry equivalent about the center of inversion by a pair of strong N-H⋯O hydrogen bond, forming inversion dimers.

1-Acetyl-6-bromo-1H-imidazo[4,5-b]pyridin-2(3H)-one.

The two fused five- and six-membered rings in the mol-ecule of the title compound, C(8)H(6)BrN(3)O(2), are approximately coplanar, the largest deviation from the mean plane being 0.011 (3) Šat the NH atom. The acetyl group is slightly twisted with respect to the imidazo[4,5-b]pyridine system, making a dihedral angle of 2.7 (2)°. In the crystal, adjacent mol-ecules are linked by inter-molecular N-H⋯N and C-H⋯O hydrogen bonds, forming infinite chains.

Ethyl 8-amino-6-bromoimidazo[1,2-a]pyridine-2-carb-oxy-late.

There are two independent mol-ecules in the asymmetric unit of the title compound, C(10)H(10)BrN(3)O(2), which are linked by N-H⋯O and C-H⋯O hydrogen bonds. The fused ring systems in both mol-ecules are nearly planar with maximum deviations of 0.001 (3) and 0.029 (3) Å. All non-H atoms of the first mol-ecule are approximately co-planar whereas in the second mol-ecule, the ethyl group is almost perpendicular to the imidazo[1,2-a]pyridine system, the C-O-C-C torsion angles in the carb-oxy-lic acid ethyl group being -179.8 (4) and 112.1 (5)°, respectively.

6-Bromo-imidazo[1,2-a]pyridin-8-amine.

The title compound, C(7)H(6)BrN(3), crystallizes with three independent mol-ecules in the asymmetric unit. The mol-ecules are approximately planar (r.m.s. deviations for all non-H atoms = 0.016, 0.023 and 0.024 Å). The primary amine groups show pyramidal coordination. In the crystal, adjacent mol-ecules are linked by N-H⋯N hydrogen bonds. For two independent mol-ecules, the amine groups are hydrogen-bond donors via one H atom to one acceptor atom, whereas for the third independent mol-ecule, the amine group is a hydrogen-bond donor to two acceptor atoms.

6-Bromo-1,3-dimethyl-1H-imidazo[4,5-b]pyridin-2(3H)-one.

The non-H atoms of the two independent mol-ecules in the asymmetric unit of the title compound, C(8)H(8)BrN(3)O, are planar (r.m.s. deviations = 0.015 and 0.019 Å). In the crystal, the mol-ecules are linked into a zigzag chain along the c axis by C-H⋯O hydrogen bonds.