wastewater

Which of the following components is/are NOT removed in the secondary treatment of sewage?

One-third of the solid matter in a sludge containing 90% water is composed of fixed mineral solids with specific gravity 2.5, and two-third is composed of volatile solids with spec...

Anaerobic bacteria are being utilized for the destruction of biodegradable organic content of wastewater measured in terms of Chemical Oxygen Demand (COD). The yield coefficient (Y...

The bacteria mainly responsible for crown corrosion in a sewer is $\qquad$

Activated carbon is used to remove a pollutant from wastewater in a mixed batch reactor, which follows first-order reaction kinetics. At a reaction rate of 0.38 /day, the time (in...

A circular settling tank is to be designed for primary treatment of sewage at a flow rate of 10 million liters/day. Assume a detention period of 2.0 hours and surface loading rate...

The wastewater inflow to an activated sludge plant is 0.5 m³/s, and the plant is to be operated with a food to microorganism ratio of 0.2 mg/mg-d. The concentration of influent bio...

The theoretical aerobic oxidation of biomass (C 5 H 7 O 2 N) is given below: C 5 H 7 O 2 N + 5O 2 → 5CO 2 + NH 3 + 2H 2 O The biochemical oxidation of biomass is assumed as a first...

For wastewater coming from a wood pulping industry, Chemical Oxygen Demand (COD) and 5-day Biochemical Oxygen Demand (BOD5) were determined. For this wastewater, which of the follo...

A wastewater sample contains two nitrogen species, namely ammonia and nitrate. Consider the atomic weight of N, H, and O as 14 g/mol, 1 g/mol, and 16 g/mol, respectively. In this w...

A wastewater sample contains two nitrogen species, namely ammonia and nitrate. Consider the atomic weight of N, H, and O as 14 g/mol, 1 g/mol, and 16 g/mol, respectively. In this w...

A 2% sewage sample (in distilled water) was incubated for 3 days at 27$$^\circ$$C temperature. After incubation, a dissolved oxygen depletion of 10 mg/L was recorded. The biochemic...

A 50 mL sample of industrial wastewater is taken into a silica crucible. The empty weight of the crucible is 54.352 g. The crucible with the sample is dried in a hot air oven at 10...

Ammonia nitrogen is present in a given wastewater sample as the ammonium ion (NH4+) and ammonia (NH3). If pH is the only deciding factor for the proportion of these two constituent...

A secondary clarifier handles a total flow of 9600 m³/d from the aeration tank of a conventional activated-sludge treatment system. The concentration of solids in the flow from the...

A grit chamber of rectangular cross-section is to be designed to remove particles with diameter of 0.25 mm and specific gravity of 2.70. The terminal settling velocity of the parti...

A river has a flow of 1000 million litres per day (MLD), BOD₅ of 5 mg/litre and Dissolved Oxygen (DO) level of 8 mg/litre before receiving the wastewater discharge at a location. F...

A stream with a flow rate of 5 m³/s is having an ultimate BOD of 30 mg/litre. A wastewater discharge of 0.20 m³/s having BOD₅ of 500 mg/litre joins the stream at a location and ins...

The wastewater from a city, containing a high concentration of biodegradable organics, is being steadily discharged into a flowing river at a location S. If the rate of aeration of...

The ultimate BOD (L₀) of a wastewater sample is estimated as 87% of COD. The COD of this wastewater is 300 mg/L. Considering first order BOD reaction rate constant k (use natural l...

The wastewater having an organic concentration of 54 mg/l is flowing at a steady rate of 0.8 m³/day through a detention tank of dimensions 2 m × 4 m × 2 m. If the contents of the t...

A wastewater sample contains $$10^{-5.6}$$ mol/l of OH - ions at $$25^o$$ C. The pH of this sample is