WASTEWATER

Waste Water Lecture Outline Health Effects of wastewater/human waste Methods of proper disposal: individual , municipal; privies, septic tanks, etc Disposal methods for developing countries Municipal treatment plants steps : screen- primary settling-aeration-secondary settling-disinfection-discharge Sludge treatment and reuse/Biosolids

DISPOSAL OF HUMAN WASTE Objectives: Prevention of human waste coming in contact with humans, animals and food Prevention of insect breeding.

Prevention of water pollution, shellfish, bathing areas, soil and air. Adherence to local, national and international standards

Field Disposal Methods of Human Waste Latrines are constructed to prevent food , soil and water contamination. They should be located at least 100 meters down stream from the water source, And down wind from residential areas. At least 5 meters above the water table

METHODS OF COLLECTION, TREATMENT AND DISPOSAL Pit privies Burn-out Latrine Cathole latrine Trench Ltrine Masonary vault privy Pail or can privy Chemical toilet

METHODS OF COLLECTION, TREATMENT AND DISPOSAL Septic Tanks Public Treatment plants

Self Contained Composting Toilet

Individual Latrines Cathole 6x6X6 inches hole. Cover after use. About 200 feet away from any water source

Field Latrines

PIT LATRINE

                                                                    HOW TO BUILD LATRINE

Select Location Dig a hole Select location at least 100 ft. from the water source It is preferable to have the location down the stream or down hill from the water source Dig a hole Mark a three foot diameter circle using 1.5 ft. string tied to a stick or nail Dig a 10 ft. hole and try to keep the side straight

Line the hole Line the hole with bricks or stones leaving two inch gaps in between The lining should extend about four inch above the ground to form a collar for the concrete slab to fit on top Measure the collar to form a concrete slab to fit on top of it Form your concrete slab with two holes one for squatting and the other to fit a vent over it

Build Superstructure Install the slab on top of the collar Build up the wall around the slab To a height of 8 feet. The squatting hole will be inside the wall while the vent hole is outside Fit a cover on top of the wall Construct a vent with a fly screen around the vent hole

Chemical toilet

Tulane/ENHS 641

THE SEPTIC TANK

Tank Capacity and Dimensions (Add 250 gallons per additional bedroom) Number Bed rooms Min.size TankReq’d (Gallons) Tank Dimension (inside) W L D 1 500 2’9” 6’1” 5’0” 2 750 3’3” 8’0” 3 900 3”9”

SCHEMATIC OF SEPTIC TANK

SEPTIC TANK FLOATING SCUM LIQUID SLUDGE INSPECTION PORT INLET OUTLET

SCHEMATIC OF SEPTIC TANK

Public Sewage Treatment Plants Screens Grit chambers Primary settling Secondary treatment: *Activated sludge and *Trickling Filters. Final settling Disinfection Disposal

BOD > 220,000 Biochemical Oxygen Demand Basically is an indication of how much putrescibie organic material is present in the water or wastewater Low BOD indicating good water quality and a high BOD reflecting polluted conditions POLLUTANT 5-day BOD (in mg/l) Raw sewage 150 – 250 Cannery waste 5000 – 6000 Discharge from pulp mills 10,000 – 15,000 Wastewater from wool scouring treatment plant effluent > 220,000

Sewage Treatment Plant Primary Settling Tank Trickling Filter Bar Screen Grit Chamber Pump Secondary Settling Tank Sludge Digester Raw sewage from sewer Chlorination (Disinfection) Discharge

FLOW DIAGRAMTRICKLING FILTER SEWAGE TREATMENT PLANT Screening Grinding Primary Settling Trickling Filter OR Activated Sludge Secondary Settling Raw Sewage Grit Chamber Coarse Screen Liquid Secondary sludge return to primary settling Sludge Chlorination Anaerobic Digestion Sludge Conditioning To receiving water Final disposal of digested dried sludge Sludge Drying

Public Wastewater Treatment Plant

Waste Stabilization Ponds/Oxidation Ponds INLET CHAMBER AERATOR OUTLET CHAMBER 8’ to 12’ SCREEN Pond loading , 15 to 35 lb of BOD/acre/day Detention time , 90 to 180 days Liquid depth , 5 ft plus 2 ft freeboard Embankment , top width 6 to 8 ft; inside outside slope 3 horizontal to 1 vertical. Pond bottom , level. Impervious, no vegetation Inlet , 4 in. diameter minimum. At center of square or circular pond Outlet , 4 in. minimum diameter, controlled liquid discharge using baffles, elbow or tee fitting.

Stabilization Ponds/Oxidation Ponds Advantages: Inexpensive to build, operate and maintain Effluent can be applied to non crop fields without disinfection. Appropriate method of disposal of human waste in warm climates. Can be used for fish propagation

Disadvantages: Good for small communities of < 2000 Does not function well in cold climates Requires disinfection if effluent is discharged in a receiving water body such as streams Aquatic plants overgrowth such as Algae blooms, Duckweed, which might cause it to become anaerobic.

Reuse of Human Waste BIOGAS * If human excreta is combined with animal and agricultural wastes, and water, it will give off gas as it decomposes. * Biogas plants typically store the wastes for about 30 days. This removes some of the pathogenic organisms but by no means all.

Recycling of Treated Human Waste Effluent: (Liquid) Treated, disinfected, waste water : irrigation for non-crop fields Bio-solids: about 5.3 billion pounds are produced in the US annually Bio-gas generation Charcoal production Land application: it is much cheaper than incineration or landfills. Saves landfill space It protects water quality, Supply nutrients to plants/Increases crop production Reduces soil erosion