Method of operating an upflow backwash filter

A method of operating at least one upflow backwash filter, wherein the upflow backwash filter contains a population of denitrifying biomass or anammox biomass or both on a filter medium, wherein the method comprises:

• receiving an overflow of a wastewater influent from a clarifier effluent collection trough or from a filter influent flocculation tank;
• receiving an outflow of the wastewater influent into a filter influent distribution channel of a liquid level control unit having at least one automatic filter influent positioning valve;
• maintaining a liquid level of the wastewater influent in the clarifier effluent collection trough or the filter influent flocculation tank or a filter influent distribution channel within a predetermined range;
• and;
• conducting the wastewater influent into the at least one upflow backwash filter;
• backwashing the backwash filter with a gas lift backwash flow wherein the gas is a non-oxygen containing gas or a blend of air with a non-oxygen containing gas when the filter medium contains thereon denitrifying biomass but not the deammonification biomass, provided the oxygen is present in an amount less than 50% of the amount in air;
• returning filter reject backwash wastewater from a rejection compartment of the upflow backwash filter through a denitrifying bacteria or anammox bacteria recycle return line to a location upstream of the upflow backwash filter;
• optionally, returning biomass from at least one of a mixed liquor flow line and a return activated sludge (RAS) flow line to a location upstream of the at least one upflow backwash filter, and
• recycling said denitrifying bacteria or anammox bacteria from said denitrifying bacteria or anammox bacteria recycle return line to any one or more of the clarifier effluent collection trough, the filter influent flocculation tank, or the filter influent flow distribution channel.

A method of operating one or more upflow backwash filters wherein the one or more upflow backwash filters contain a population of denitrifying biomass or deammonification biomass (anammox bacteria) or both on a filter medium, wherein the method comprising:

• receiving an overflow of a wastewater influent from a clarifier basin in a clarifier effluent collection trough;
• optionally, receiving an outflow of the wastewater influent from the clarifier effluent collection trough in a filter influent flocculation tank;
• receiving an inflow of the wastewater influent from the clarifier effluent collection trough or the filter influent flocculation tank in a filter influent flow inlet distribution channel;
• maintaining a substantially constant liquid level in filter influent distribution channel;
• applying hydrostatic pressure to push the wastewater influent from the filter influent flow inlet distribution channel into the one or more upflow backwash filters;
• backwashing the backwash filter with a gas lift backwash flow wherein the gas is selected from the group consisting of air, a non-oxygen containing gas or a blend of air with a non-oxygen containing gas;
• wherein the filter backwash rate, volume, time, time intervals or a combination of therein is controlled to keep sufficient biomass accumulation in the filter in order to maintain the liquid level in the upstream filter influent distribution channel at an elevation sufficient to minimize the hydraulic head drop from the upstream treatment units and minimize the aeration of dissolved oxygen (DO) concentration in the filter influent wastewater;
• returning filter reject backwash wastewater from a rejection compartment of the one or more up flow backwash filters through a denitrifying bacteria or anammox bacteria recycle return line to a location upstream of the upflow backwash filter;
• optionally, returning biomass from at least one of a mixed liquor flow line and a return activated sludge (RAS) flow line to the location upstream of the upflow recycling said denitrifying bacteria or anammox bacteria from said denitrifying bacteria or anammox bacteria recycle return line to at least one of said clarifier effluent collection trough, said filter influent flocculation tank, the filter influent flocculation tank, or the filter influent flow distribution channel.