3-Diethyl­amino-6-[(Z)-(4-hy­droxy­anilino)methyl­idene]cyclo­hexa-2,4-dienone

In the mol­ecule of the title compound, C17H20N2O2, the aromatic rings are oriented at a dihedral angle of 6.23 (22)°. Intra­molecular N—H⋯O hydrogen bonding involving the amine H atom and the carbonyl O atom affects the conformation of the mol­ecule. One of the ethyl arms is disordered over two conformations, with occupancies of 0.59 (2) and 0.41 (2). The crystal packing is stabilized by inter­molecular C—H⋯O and O—H⋯O hydrogen bonds, and weak C—H⋯π inter­actions

Poly[triaquabis­(μ2-3-carboxy­pyrazine-2-carboxyl­ato)dilithium(I)]

In the title compound, [Li2(C6H3N2O4)2(H2O)3]n, the coordination number for both independent Li+ cations is five. One of the Li+ ions has a distorted trigonal–bipyramidal geometry, coordinated by one of the carboxyl O atoms of a 3-carboxy­pyrazine-2-carboxyl­ate ligand, two O atoms from two water mol­ecules, and an N and a carboxyl­ate O atom of a second 3-carboxy­pyrazine-2-carboxyl­ate ligand. The other Li+ ion also has a distorted trigonal–bipyramidal geometry, coordinated by one water mol­ecule and two 3-carboxy­pyrazine-2-carboxyl­ate ligands through an N and a carboxyl­ate O atom from each. One of the carboxyl groups of the two ligands takes part in an intra­molecular O—H⋯O hydrogen bond. The stabilization of the crystal structure is further assisted by O—H⋯O, O—H⋯N and C—H⋯O hydrogen-bonding inter­actions involving the water mol­ecules and carboxyl­ate O atoms

2-Methyl-6-[2-(trifluoro­meth­yl)phenyl­imino­meth­yl]phenol

The title compound, C15H12F3NO, is a Schiff base which adopts the phenol–imine tautomeric form in the solid state. The dihedral angle between the aromatic rings is 38.79 (5)°. The mol­ecular structure is stabilized by an intra­molecular O—H⋯N hydrogen bond, which generates an S(6) ring. In addition, there is an intra­molecular short C—H⋯F contact

4-Methyl-N-[(S)-1-phenyl­eth­yl]benzene­sulfonamide

In the title compound, C15H17NO2S, the dihedral angle between the aromatic rings is 14.47 (8)°. The mol­ecule is bent at the N atom, with a C—SO2—NH—C torsion angle of 79.06 (13)°. In the crystal structure, the sulfonamide groups are hydrogen bonded via N—H⋯O links, forming chains of mol­ecules along the crystallographic b axis. π–π inter­actions [centroid–centroid distance = 3.81 (3) Å] also occur

(Z)-6-[(5-Chloro-2-hydroxy­phenyl)­aminomethyl­ene]-2-ethoxy­cyclo­hexa-2,4-dienone

The title compound, C15H14ClNO3, exists as the keto–amine form in the crystal and two intra­molecular N—H⋯O hydrogen bonds are observed. The aromatic rings are oriented at a dihedral angle of 5.85 (8)°. In the crystal structure, inter­molecular O—H⋯O and C—H⋯O hydrogen bonds link the mol­ecules into chains. A π–π contact between the benzene rings [centroid–centroid distance = 3.6623 (10) Å] further stabilizes the structure

Use of Natural Zeolite to Upgrade Activated Sludge Process

The objective of this study was to achieve better efficiency of phosphorus removal in an enhanced biological phosphorus removal process by upgrading the system with different amounts of natural zeolite addition. The system performance for synthetic wastewater containing different carbon sources applied at different initial concentrations of phosphorus, as well as for municipal wastewater, was investigated. Natural zeolite addition in the aerobic phase of the anaerobic/aerobic bioaugmented activated sludge system contributed to a significant improvement of phosphorus removal in systems with synthetic wastewater and fresh municipal wastewater. Improvement of phosphorus removal with regard to the control reactors was higher with the addition of 15 than with 5 g/L of natural zeolite. In reactors with natural zeolite addition with regard to the control reactors significantly decreased chemical oxygen demand, ammonium and nitrate, while higher increment and better-activated sludge settling were achieved, without changes in the pH-values of the medium. It was shown that the natural zeolite particles are suitable support material for the phosphate-accumulating bacteria Acinetobacter calcoaceticus (DSM 1532), which were adsorbed on the particle surface, resulting in increased biological activity of the system. The process of phosphorus removal in a system with bioaugmented activated sludge and natural zeolite addition consisted of: metabolic activity of activated sludge, phosphorus uptake by phosphate-accumulating bacteria adsorbed on the natural zeolite particles and suspended in solution, and phosphorus adsorption on the natural zeolite particles

(E)-2-[(4-Ethoxy­phen­yl)imino­meth­yl]-4-methoxy­phenol

In the mol­ecule of the title compound, C16H17NO3, the aromatic rings are oriented at a dihedral angle of 29.25 (8)°. An intra­molecular O—H⋯N hydrogen bond results in the formation of a nearly planar [maximum deviation 0.034 (13) Å] six-membered ring, which is oriented at dihedral angles of 0.91 (1) and 28.91 (12)° with respect to the aromatic rings. The title mol­ecule is a phenol–imine tautomer, as evidenced by C—O, C—N and C—C bond lengths. In the crystal, mol­ecules are linked by inter­molecular C—H⋯O hydrogen bonds that generate C(8) chains

2-{2-[4-(4-Fluoro­phen­yl)piperazin-1-yl]-2-oxoeth­yl}-6-(morpholin-4-yl)-4-phenyl­pyridazin-3(2H)-one

In the title compound, C26H28FN5O3, the morpholine ring adopts a chair conformation. The piperazine ring is puckered [Q T = 0.5437 (15) Å, θ = 8.89 (15) and ϕ = 357.2 (11)°]. The 1,6-dihydro­pyridazine ring makes dihedral angles of 28.03 (7) and 77.46 (7)° with the phenyl and benzene rings, respectively. In the crystal, mol­ecules are linked along the c axis by C—H⋯O inter­actions and are flattened parallel to the ac plane. C–H⋯π inter­actions also contribute to the stability of the structure