SYSTEMS AND METHODS FOR TREATMENT OF WATER, SUCH AS OILFIELD WASTEWATER, VIA CHEMICAL COAGULATION

摘要

Described herein are systems and methods for treating an aqueous input stream comprising at least one suspended and/or emulsified immiscible phase (e.g., oil, grease) and, in some cases, one or more additional contaminants, such as solubilized bicarbonate (HCO₃⁻) ions, solubilized divalent cations (e.g., Ca²⁺, Mg²⁺), solubilized trivalent cations (e.g., Fe³⁺, Al³⁺), organic material (e.g., humic acid, fulvic acid), hydrogen sulfide (H₂S), and/or suspended solids. According to certain embodiments, the aqueous feed stream is supplied to a water treatment system comprising a chemical coagulation apparatus and a suspended solids removal apparatus (e.g., a clarifier). Within the chemical coagulation apparatus, an amount of an inorganic coagulant (e.g., aluminum chlorohydrate, polyaluminum chloride), an amount of a strong base (e.g., sodium hydroxide), and an amount of a polyelectrolyte (e.g., polyacrylamide) may be added to the aqueous input stream to form a chemically-treated stream. In some embodiments, the inorganic coagulant, strong base, and/or polyelectrolyte may induce coagulation and/or flocculation of at least a portion of the contaminants within the aqueous input stream, and the chemically-treated stream may comprise a plurality of flocs (i.e., particle agglomerates). In some embodiments, the chemically-treated stream is directed to flow to the suspended solids removal apparatus. Within the suspended solids removal apparatus, a plurality of flocs may be removed from the chemically-treated stream to form a contaminant-diminished stream having a lower concentration of contaminants than the aqueous input stream. In some embodiments, the chemically-treated stream and the contaminant-diminished stream each have a pH of about 8 or less. In some embodiments, the chemically-treated stream and the contaminant-diminished stream each have a temperature of about 15° C. or less.