Alternative Solutions For Wastewater Treatment Focus in Communities with Low Income. By Cesar A. Hernandez Class: Aquatic Plants November 2, 2006 University

Alternative Solutions For Wastewater Treatment Focus in Communities with Low Income.

By Cesar A. Hernandez

Class: Aquatic Plants

November 2, 2006

University of Arizona

Amount of Water Used Daily/countries (liters)

Country Water (L)

USA 6320Canada 4130Australia 3320Italy 2960Netherlands 2730Spain 2650Japan 2530Germany 1870France 1370United Kingdom 700Denmark 650Switzerland 290Mexico 200Somalia 9

Cesar Hernandez,2006

Water used by American people (each person).

Water use lts. Gallons percent of use

Washing/showering 216 57 27 Toilet flushing 192 50 24

Running washing machine 136 36 17

Doing dishes 112 30 14

Cooking/drinking 80 21 10

Gardening/ washing cars 64 17 8

Totals 800 lts. 211 gallons 100


Why is so important to treat wastewater

Inadequate wastewater treatment often leads to severe water quality and public health problems.

There are a lot of communities in which people have low budget and low income. Some times, these communities have no electricity, running water or plumbing for waste disposal.

What is the result of this situation:

a).- High disease incidence rater b).- Migratory population can contribute to the diffusion of diseases.

This problem occurs no only in countries in development, but also here in the US. Basically in the border with Mexico (El Paso TX. and Cd. Juarez Chihuahua)

Cesar Hernandez, 2006

Characteristics of the Wastewater Farmers face strict regulations concerning disposal of animals waste.

Industry generates wastewaters as it products society uses.

Local landfills produce wastewater in the form runoff.

The highway department applies chemicals to roads to melt snow and ice.

Heavy rains wash the oil and grease from roadways and carry topsoil and nutrients (like N and P) into streams or rivers.

Some of these wastewater leaches into the groundwater that is used for cleaning, cooking and drinking.

Some waters runs into streams, rivers and bays where it can kill fish, shellfish and plants.


Why treat wastewater. Water is a limited source, although 70 % of earth is cover with water, only 3% is fresh water.

< 1% of the world's fresh water is accessible for direct human uses. A).- About 1/3 of world's population does not have enough drinking water B).- Almost half of world's land is without water C).- Converting arid land to fertile land can reduce global warming

D).- Better technology would give us greater access to freshwater

Wastewater has an extremely large number of water borne bacteria and pathogens.

Dirty wastewater can carry disease into water.

It contains high levels of nitrogen and phosphorus. with nitrogen being mainly in the form of ammonia.


What Diseases Are Commonly Caused By Wastewater

Caused by 1.- Typhoid fever (Salmonella typhi)Bacteria: 2.- Cholera (Vibrio Cholerae)

Caused by 3.- Viral gastroenteritis (Salmonella, Escherichia colli and Giardia L.)Viruses: 4.- Hepatitis A (HBV)

5.- Poliomyelitis (Nile virus )

Caused by 6.- Giardiasis (Giardia Lambia)Parasites: 7.- Cryptosporidiosis (Cryptosporidium) 8.- Amebic dysentery (Entamoeba histolytica)


Place in necessity..Place in necessity


Main problem

Other negative effects..

Nitrogen phosphorus causing algae blooms.

Algae blooms cause Oxygen affecting the fish.

Nitrogen can cause methemoglobinemia, or blue baby syndrome.

Metals, such as cadmium, copper, lead, nickel, and zinc, can also be found in wastewater and cause harmful in larger doses (periods).

Excess nutrients in coastal waters may also be related to certain “Red Tides”.


Algae blooms: Are microscopic plants that are usually aquatic, unicellularand lack of true stems, roots, and leaves. Produces harmful toxins.

How Wastewater Treatment Helps Prevent negative effects

Wastewater treatment, consists of a combination of processes used in steps to remove, kill, or “inactivate” a large portion of the pollutants and disease-causing organisms in wastewater.

First, solid materials are filtered out or allowed to settle and separate from the rest of the wastewater.

The wastewater receives further treatment often through a combination of filtration and biological and chemical processes. Liquids are often stored for a period of time to allow further settling and bacterial treatment.

The sludge is then treated further by applying lime or chemicals, air drying, heat drying, or composting.

final disposal, it is burned, buried in landfills, used as commercial fertilizer, spread on forested land, or disposed of in the ocean.

Disinfection is normally the final treatment step for wastewater Chlorine, ozone, ultraviolet light, or other chemical agents inactivate many pathogens.


Objectives

Evaluation and analyses of socio-economic, physical and technological factors to select wastewater treatment alternatives for low income communities.

Identify an appropriate wastewater treatment system in communities with low income.


Methodology

In order to know appropriate wastewater treatment system must be considered several elements .

It is necessary to determine the size of the system based in the wastewater average usage volume per household per day.

Development an economic analysis, represented by the costs per household.

Evaluate the rates of concentration of pollutants and pathogens in every system.

Carry out a technical appraisal on aspects such as physical environment and technical feasibility.


Technologies for wastewater treatment.

Sand Filtration

Trickling filters

Constructed treatment wetlands

Subsurface injection

Stabilization ponds

Aerated and Facultative lagoons

On–site septic systems

Activated Sludge process


General Criteria to evaluate technology

Wastewater treatment efficiency.

Physical environment.

Legal end socioeconomic considerations.

Technological feasibility.

Adaptability and complexity.

Viable lifetime.


The evaluative criteria for this analysis were based in BECC’s

BECC’s “Guidelines for project submission and criteria for project certification”.

Similar criteria was used in a research called Appropriate Sanitation Alternatives: A technical and Economic Appraisal (Gunnnerson,1982).


Physical Constraints Criteria

1.- System’s compatibility with the local

Physical environment.

2.- The ability to remove pollutants and

pathogens from household.


A comparison of Criteria Used by Gunnerson for this studies

Cesar Hernandez. 2006Appropriate Sanitation Alternatives: A Technical and Economic

Appraisal criteria

Comparable Criteria Employed in this Analysis

Construction Cost

Operating cost

Ease of construction

Water Requirement

Required Soil Conditions

Reuse Potential and Health Benefits

Institutional Requirement

Capital cost

Operation and Maintenance costs

Technological Feasibility

Compatibility with Existing Infrastructure

Compatibility with Physical Environment

Amount and Type of Pollutant/Pathogen removedPermitting


Amount and type of pollutants/Pathogens

removed This analysis evaluates the removal efficiencies of proposed wastewater

treatment in each system in regards to:

o Biological Oxygen Demand (BOD5)

o Total suspended solids (TSS)

o Total Nitrogen (N)

o Fecal Coliform

o Viruses

The Arizona Department of Water Resources (DWR) and the Department of Environmental Quality (DEQ).


Characteristics of Sand Filtration SystemSand filtration is high effective at removing pollutants and pathogens.

This system meets all TNRCC standards for effluent discharge.

BOD5 is reduced to less than 5 mg/L by a standard sand filter, according to some studies.

Sand filters are suited to semi-arid environments such as the southwest.

Changes in the temperature affects the biological activity in the filter, and hence its performance.

The flat topography is not ideal for sand filters.

This system is often used in conjunction with septic tanks.

Operation and maintenance costs are low for sand filters.

Is considered an efficient system in wastewater.

Cesar Hernandez. 2006

Characteristics of On -site Septic System

This System treat domestic wastewater in up to three different redox environments that form as the system develops.

The concentration of organic matter in this environment is high.

The biological mat is a limiting factor in the wastewater infiltration rate.

The metal cation such as CU, Cr, Pb and Zn usually remain in the septic tank because they form insoluble sulfides.

Cold temperatures can potentially slow biodegradation of effluent in the leach field.

Septic systems require low technological complexity.

They do not meet the pollutant standards.

In this system is required annually to remove sludge and prevent fouling of the system.


Waste Stabilization Ponds

Also called Lagoons, provide a cheap alternative to conventional process.

Lagoons, treat wastewater through the use of sunlight, wind, algae and oxygen.

In an aerated lagoon, aeration equipment is installed to provide additional oxygen.

Lagoons are simple to operate – effective automatic operation with minimum monitoring.

The effect of odor impact can be readily controlled by covering the anaerobic areas or applying aeration.

Lagoons required large areas for implementation.

Only about 80% maximum BOD removal is possible.

Lagoons are strongly affected by atmospheric conditions.

For BOD5, TSS and total Coliform, ponds removal efficiencies are not sufficient to meet the effluent standards.


Characteristics of Constructed Treatment WetlandsWetlands can transform common pollutants that occur in wastewaters into harmless products.

The microbial activity include oxidation of organic matter and transformation of nutrients.

These transformations can be obtained for relatively low cost of earthwork, piping, pumping and concrete structures.

Are one of the least expensive treatment systems to operate and maintain.

The water saturated conditions in wetlands reduce gas exchange rates between the sediments and the atmosphere. Then the sediments become anoxic or anaerobic.

Wetlands seem to be effective at retaining significant loads of several trace metals.

Wetlands vegetation plays an integral role in treatment by transferring oxygen providing a medium for microorganisms that perform most of the biological treatment.

Can provide greater thermal protection in cold climates.

The wetlands can be used for commercial crop production.


Graphical representation of the treatment processes that Wetland System

.


Calculate on minimum wastewater demand for the region.

1.- Number of housing

2.- Number of residents per housing

3.- Wastewater usage volume average per day

4.- Estimated growth rate per year (Projecting).


Projecting the total population from 2000 to the year 2015, using an estimated growth rate of 3%

Area: South TucsonCurrent Population:5,490 Households: 1,810Number of residents per housing: 3Wastewater usage volume/person/day:800 lts or 211 gallonsWastewater usage volume/household/day: 2400 lts or 635 gallons

Population by 2015 (2015- 2000)

Pop 2015 = Pop 2000 * (1 + annual growth rate) 15

Pop 2015 = 5,490 (1.03 )

Pop 2015 = 8,553 persons

Minimum wastewater demand

Volume = 635 gallons/day/household * 8,553 / 3 persons/household Volume = 635 gallons * 2,851 household = 1,810,000 GPD Cesar Hernandez,2006

Results and Conclusions

The purpose of this study was the analysis of appropriate wastewater treatment alternatives.

The construction of wetlands got the most high score from all of the systems for treat wastewater, and Sand Filtration System was the second. However, every region has particular characteristics.

The physical, technological and economic constraints of implementing a particular treatment system, must be considered in each appraisal.

The value ranges for each community, can be expanded to meet the data requirements for the specific site.

It is so important create a new culture in communities with low income. The families that are living in rural zones, must know the importance of establish systems treating wastewater.

To prevent major health problems, like the spread of some infections, it is necessary to create educative programs about the importance of wastewater treatment.


Thanks for pay Attention

Questions?


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Alternative Solutions For Wastewater Treatment Focus in Communities with Low Income. By Cesar A. Hernandez Class: Aquatic Plants November 2, 2006 University