A method for controlling a hydrogen sulfide concentration of a wastewater stream, the method including measuring a hydrogen sulfide concentration in one phase of the wastewater stream. At least one additional parameter of the wastewater stream is measured, and a hydrogen sulfide concentration of the other phase of the wastewater stream is calculated with a mathematical model that characterizes the hydrogen sulfide concentration in the other phase based on a set of variables that includes the measured hydrogen sulfide concentration in the one phase and the measured at least one additional parameter. Based on the calculated hydrogen sulfide concentration of the other phase, a treatment dosage of a treatment agent that reduces the hydrogen sulfide concentration of the wastewater stream is determined and applied to the wastewater stream.

Some aspects of the invention can involve compositions, systems, and related techniques that control or reduce objectionable odor characteristics of a body or a stream of wastewater. The compositions, systems, and related techniques can comprise one or more compounds that adjust metabolic activity of at least a portion of microorganisms in wastewater to inhibit or disfavor the formation of at least one objectionable odorous compound or species and one or more compounds that modify, shift, or promote one or more states or characteristics of one or more objectionable odorous species in wastewater. The metabolic modifying compound can be an anthraquinone and the state modifying compound can be an alkaline or pH-elevating compound.

Methods of controlling hydrogen sulfide concentration of a biogas occupying an anaerobic membrane bioreactor (AnMBR) containing a submerged membrane are disclosed herein. Methods of controlling dissolved sulfide concentration of a mixed liquor within the AnMBR are disclosed. The methods include directing wastewater containing sulfur and a chemical oxygen demand (COD) to an AnMBR, withdrawing at least a fraction of the biogas from the AnMBR, directing a pre-determined amount of the withdrawn biogas to a scrubber, directing a remainder of the withdrawn biogas to a gas distributor, and directing the scrubbed biogas to the AnMBR. Systems for treating wastewater having sulfur and COD are disclosed. The systems include an AnMBR, a scouring gas closed loop, a scrubber, and a control mechanism for directing biogas to the scrubber and to a gas distributor. Methods of retrofitting a system for treating wastewater having sulfur and COD are disclosed.