A system for treating wastewater containing selenium has a sequencing batch reactor upstream of a fixed film reactor. The sequencing batch reactor may be operated under anoxic conditions while influent is mixed with residual sludge. The SBR reduces total nitrogen, suspended solids, or both. Selenium is removed in the fixed film reactor by biological reduction to elemental selenium.

Systems and methods are described for treating flue gas, for example from a coal fired power plant. The systems and methods include control of a wet flue gas desulfurization (WFGD) system to manage sulfite concentration in a slurry produced by the WFGD system. Oxygen is added to the slurry in an amount sufficient to produce a sulfite concentration in the slurry in the range of about 5 to 75 mg/L, an oxidation reduction potential in the range of about 100-250 mV, or both. The systems and methods also include the biological treatment to remove selenium from a liquid fraction of the slurry. The liquid fraction is treated in a biological reactor maintained under anoxic or anaerobic conditions to reduce its selenium concentration.

The invention relates to bio-electrochemical systems for treating wastewater, and sour gas produced by anaerobic digestion of organic material. The invention further relates to novel anode/cathode pairing schemes, and electric and hydraulic architectures for use in bio-electrochemical systems.

A river course ecological treatment system for use in a river includes a plurality of plastic retaining dams disposed in the river that receive and divide the river course into sequential retaining regions arranged in a direction from upstream to downstream; a plurality of ecological biological water purification systems disposed in the sequential retaining regions and each ecological biological water purification system being located between any two adjacent plastic retaining dams of the plurality of plastic retaining dams to purify water within the sequential retaining regions and discharge purified water; and at least one damp land ecological water purification system that is disposed beside the river and that includes a rainwater channel disposed along the river; aquatic plants disposed in the rainwater channel are effective to purify water flowing within the rainwater channel; and draining vents provided in the rainwater channel that discharge purified water into the river course.

The field of advanced wastewater treatment, and more specifically, to a natural pyrrhotite biofilter and a method for utilizing same to synchronously remove nitrate-nitrogen and phosphorus from water is provided. The method includes the following steps: (1) preparation of the packing material and construction of the biofilter; (2) start-up of the biofilter; (3) operation of the biofilter. The method disclosed in the present invention on the one hand takes pyrrhotite as the electron donor to help sulfur-based autotrophic denitrifying bacteria reduce nitrates into nitrogen gas, and on the other hand utilizes pyrrhotite and its oxidates to eliminate phosphorus through adsorption and chemical precipitation. Therefore, this method realizes synchronous removal of nitrate-nitrogen and phosphorus in water.

Devices are provided herein for the purification of free flowing or semi-free flowing bodies of water by removing impurities, such as nitrates. In one or more implementations, the impurity-removing device includes a cylindrically shaped housing that is open on both ends and defining an inner cavity. A cap is disposed at one opening at one end of the housing, the cap having multiple openings placed through the cap and being sized and shaped to fit the opening at the end of the housing. The impurity-removing device also includes a collection strip on an outer surface of the housing that is colored, sized and shaped to collect heat or energy from the environment, and an impurity-removing medium contained within the inner cavity.

An upflow continuous backwash deep bed sand filter (UCBF) having a recycle line for returning carbonaceous denitrifying bacteria attached to biomass to the influent of the UCBF. The recycle line returns the biomass to the treatment process at a location upstream of the upflow continuous backwash filter. Further, a liquid level control unit is provided that reduces fluctuations and significant drop in the liquid level upstream of the upflow continuous backwash filter, thereby avoiding or minimizing flow turbulences, air induction, and undesirable wastewater aeration resulting in the need to dose excessive carbon source to remove dissolved oxygen in the aerated wastewater.

A filter system for removing and/or neutralizing undissolved oils, greases, and salts on/in water-containing emulsions from, in particular, tanks and baths that are used to hold and store emulsions, which are used to cool and lubricate workpieces and tools during machining, comprising at least one emulsifier filter, a downstream suction/pressure pump, a unit for gas enrichment, an adhesion filter having an automatic deaerator, a downstream oil-collecting vessel, and a capillary filter, wherein these are combined as a unit, such that the oil/grease film and the emulsion can be mechanically, chemically, and biologically treated.

A river course ecological treatment system essentially comprises a plurality of ecological biological water purification systems and a plurality of plastic retaining dams disposed along a river course, and at least one damp land ecological water purification system disposed beside the river course. The plastic retaining dams separate the river course into several retaining regions. The ecological biological water purification systems purify the water in the retaining regions by microorganism purification. Afterward, the water purified by the ecological biological water purification systems is introduced into rainwater channels of the at least one damp land ecological water purification system. After being purified by aquatic plants in the at least one damp land ecological water purification system, the water returns to the retaining regions the downstream portion of the river course. Therefore, a river improvement system capable of performing both step-by-step treatment and joint treatment is effectuated.

Devices are provided herein for the purification of free flowing or semi-free flowing bodies of water by removing impurities, such as nitrates. In one or more implementations, the impurity-removing device includes a cylindrically shaped housing that is open on both ends and defining an inner cavity. A cap is disposed at one opening at one end of the housing, the cap having multiple openings placed through the cap and being sized and shaped to fit the opening at the end of the housing. The impurity-removing device also includes a collection strip on an outer surface of the housing that is colored, sized and shaped to collect heat or energy from the environment, and an impurity-removing medium contained within the inner cavity.