NH International (Caribbean) Ltd Penal Rock Hindu School Presented by : Sudesh Ramroop

DESIGN BRIEF The proposed Sewerage Treatment Plant is sized in accordance with the following guidelines: The proposed Sewerage Treatment Plant is sized in accordance with the following guidelines: Capacity x Average Daily Flow Rate Example:300 x (55 Liters per Person /3.78) = Gallon of Waste Water per day Example:300 x (55 Liters per Person /3.78) = Gallon of Waste Water per day

INLET & OUTLET QUALITY The proposed Sewerage Treatment Plant is designed to treat domestic wastewater. Domestic Wastewater is essentially the spent or used water of a community, emanating from personal, sanitation and domestic uses. It is intended for the discharge from the treatment process to be integrated into inland surface water according to TTS 417:1993. The proposed Sewerage Treatment Plant is designed to treat domestic wastewater. Domestic Wastewater is essentially the spent or used water of a community, emanating from personal, sanitation and domestic uses. It is intended for the discharge from the treatment process to be integrated into inland surface water according to TTS 417:1993. Influent waste water BOD= 280 mg/l Influent waste water BOD= 280 mg/l Maximum Permissible Levels of Key Parameters for Liquid Effluent from Domestic Wastewater Treatment Plants Maximum Permissible Levels of Key Parameters for Liquid Effluent from Domestic Wastewater Treatment Plants Point of Discharge:Inland Surface Waters Point of Discharge:Inland Surface Waters 5 Day BOD (mg/l)25 5 Day BOD (mg/l)25 Suspended Solids30 Suspended Solids30 pH6-9 pH6-9 Faecal Coliform4000 Faecal Coliform4000 Total Residual Chlorine Total Residual Chlorine (mg/l)0.1 (mg/l)0.1 Source: Trinidad & Tobago Standards- Specifications for the Liquid Effluent from Domestic Wastewater Treatment Plants into the Environment. TTS 417:1993 Source: Trinidad & Tobago Standards- Specifications for the Liquid Effluent from Domestic Wastewater Treatment Plants into the Environment. TTS 417:1993

WASA GUIDLINES WASA requires that you allow 280 Liters per person and 4.5 persons per house in all design calculations per details below- However, a study was completed by ECO Projects Limited verifying the capacity used per household and a figure of 250 Liters was recommended. WASA requires that you allow 280 Liters per person and 4.5 persons per house in all design calculations per details below- However, a study was completed by ECO Projects Limited verifying the capacity used per household and a figure of 250 Liters was recommended.

INNFLUENT QUALITY

EFFLUENT QUALITY

SEPTIC TANK SECONDARY TREATMENT TERTIARY TREATMENT TREATMENT STAGES

AEROBIC TREATMENT UNIT

An aerobic treatment unit (ATU) pretreats wastewater by adding air to break down organic matter, reduce pathogens, and transform nutrients. Compared to conventional septic tanks, ATUs break down organic matter more efficiently, achieve quicker decomposition of organic solids, and reduce the concentration of pathogens in the wastewater. More than 20 brands of ATUs are available, but efficiency varies widely. A properly operating ATU should produce high-quality effluent with less than 30 mg/liter BOD (biochemical oxygen demand, a measure of the organic matter), 25 mg/liter TSS (total suspended solids), and 10,000 cfu/100mL fecal coliform bacteria, an indicator of pathogens and viruses. An aerobic treatment unit (ATU) pretreats wastewater by adding air to break down organic matter, reduce pathogens, and transform nutrients. Compared to conventional septic tanks, ATUs break down organic matter more efficiently, achieve quicker decomposition of organic solids, and reduce the concentration of pathogens in the wastewater. More than 20 brands of ATUs are available, but efficiency varies widely. A properly operating ATU should produce high-quality effluent with less than 30 mg/liter BOD (biochemical oxygen demand, a measure of the organic matter), 25 mg/liter TSS (total suspended solids), and 10,000 cfu/100mL fecal coliform bacteria, an indicator of pathogens and viruses.

How Do Aerobic Treatment Units Work? By bubbling compressed air through liquid effluent in a tank, ATUs create a highly oxygenated (aerobic) environment for bacteria, which uses the organic matter as an energy source. In another stage bacteria and solids settle out of the wastewater and the cleaner effluent is distributed to a soil treatment system or water course. By bubbling compressed air through liquid effluent in a tank, ATUs create a highly oxygenated (aerobic) environment for bacteria, which uses the organic matter as an energy source. In another stage bacteria and solids settle out of the wastewater and the cleaner effluent is distributed to a soil treatment system or water course.

ATUs are more complicated than septic tanks. In a septic tank, solids are constantly separating from liquid. As individual bacterial cells grow, they sink to the bottom, along with less decomposed solids, to form a layer of sludge. Floating materials, such as fats and toilet paper, form a scum layer at the top of the tank. ATUs are more complicated than septic tanks. In a septic tank, solids are constantly separating from liquid. As individual bacterial cells grow, they sink to the bottom, along with less decomposed solids, to form a layer of sludge. Floating materials, such as fats and toilet paper, form a scum layer at the top of the tank. In an ATU, the bubbler agitates the water so solids cannot settle out, and floating materials stay mixed in the liquid. Well-designed ATUs allow time and space for settling, while providing oxygen to the bacteria and mixing the bacteria and its food source (sewerage). Any settled bacteria must be returned to the aerobic portion of the tank for mixing and treatment. In an ATU, the bubbler agitates the water so solids cannot settle out, and floating materials stay mixed in the liquid. Well-designed ATUs allow time and space for settling, while providing oxygen to the bacteria and mixing the bacteria and its food source (sewerage). Any settled bacteria must be returned to the aerobic portion of the tank for mixing and treatment.