PHYSICAL QUALITY PARAMETERS OF DRINKING WATER

The drinking water should have the following physical properties:

1) Suspended solids

2) Turbidity

3) Color

4) Taste & Odor

5) Temperature

1) Suspended solids :-

In the drinking water the suspended solids should not be present even in small amounts.

For drinking water the suspended solids must be zero.

Acceptable limit of suspended solids: Zero.

2) Turbidity :-

The word turbidity indicates that the property of obstructing the light through it. The turbidity of water can be determined by Jackson's Turbidimeter, Baylis Turbidimeter, Nephelometer.

Acceptable limit of suspended solids:- 1 JTU (Jackson Turbidity Units)

Rejectable limit :- 5 NTU (Nephleometer Turbidity Units).

3) Color :-

The drinking water should be color less because the color indicates that impurities present in the water. 

Acceptable limit of color :- Colorless

4) Taste & Odor :-

The taste of the drinking water should be comfortable to consume and it should not impart bitter taste.

The odor of the water should not impart bad smell. The units to measure odor is Threshold odor number.

5) Temperature :-

The drinking water is acceptable when it contains 10o C to  25o C

If temperature of water < 10o C -- difficult to consume

If temperature of water > 25o C -- biological reaction

Special Thanks to CHINTHA TEJA

STREET LIGHTING

Objectives of street lighting:

The objectives of street lighting are

1) Ensure that fast traffic moves safely,
2) Facilitates pedestrian movements,
3) Ensure that pedestrians and vehicle drivers recognize obstacles; and enhance security,
4) The first is only important for through routes. In residential areas, where traffic moves slowly, it will not be an important concern.

Definitions and description:

The lamp is the source of light, which converts electrical energy into radiation. The main types of lamps in use are:

1) Tungsten lamps (designated GLS): in which a small wire contained in a glass bulb is heated to a high temperature in a vacuum.

2) Fluorescent lamps (designated MCF and TL): in which ultra-violet radiation causes phosphor powder to glow inside a tube.

3) Discharge lamps: in which an electric current is passed through a mixture of gasses in a sealed tube. Examples are low-pressure sodium, high pressure sodium and high pressure mercury (designates SOX, SON and MBF or HPL-N respectively).

The lantern refers to the complete street lighting fixture, including the lamp and the pole or other means of raising it above the street

The luminous flux represents the quantity of radiation emitted by a lamp, measured in units of lumens.

The intensity of light by a lamp is measured in units of candelas.

The Luminance of a point on the road surface that is receiving light from a lantern equals the intensity of the light emitted by the lamp divided by the square of the distance of the point from the lamp.

It relates to the incident light falling on a surface and so is higher close to the lamp. It is measured in terms of lux (Lumens per square metre).

Another measure of the intensity of light is Luminance, which is a measure of the light reflected from the road surface. It is measured in candelas per square metre.

It is commonly used to assess lighting requirements for heavily trafficked roads and has limited relevance to the needs of low-income areas.

ANGANWADI BUILDING PLANS IN ANDHRAPRASEDHA

 

Credits: Architech Engineers, hyderabad

WASTE WATER TREATMENT

 Waste water and its characteristics:

The waste water  which is generated from 'kitchens, bathrooms, and other wash areas' is called "Grey water".
The waste water which is generated from 'Toilets' is called "Black water".

Grey water + Black water = Waste water

          In general, 80% of water used by the population comes out as waste water. If the water availability is 135 lpcd (Municipal+other sources), we consider 108 lpcd as the waste water generation. 

General characteristics of waste water is presented as below:

PARAMETER	HIGH	MEDIUM	LOW
COD Total	1,200	750	500
COD Soluble	480	300	200
COD Suspended	720	450	300
BOD	560	350	230
VFA (as acetate)	80	30	10
N total	100	60	30
Ammonia-N	75	45	20
P total	25	15	6
Ortho-P	15	10	4
TSS	600	400	250
VSS	480	320	200

What is Faecal sludge and septage?

The sludge produced by on-site sanitation systems like septic tanks is called "Septage".

The slude produced from pit toilets is called "Faecal sludge".

It is highly polluting than domestic waste water.

Faecal sludge quantity and quality

Supply based: It is estimated that 230 lts of Faecal Sludge is produced per capita per year.

Demand based: No.of septic tank emptying incidents X Capacity of the septic tank cleaning truck

Characteristics of Faecal sludge/septage is presented below:

Constituent All are units but for PH are in mg/l	Average
PH	1.5 - 12.6
Total suspended solids	12,862
Biochemical oxygen demand	6,480
Chemical oxygen demand	31,900
Ammonia-Nitrogen	97

 

Faecal sludge Management system (FSM):

Source: Bill And Gates Foundation

WORKABILITY OF CONCRETE !! SLUMP TEST ON CONCRETE

          Slump test on concrete is performed to check the concrete workability. A good workable concrete possesses good strength.

What is workability of concrete?

          Workability of concrete is defined as how easily concrete can be mixed, transported, consolidated, and placed in position in a homogenious state. Workability of concrete impacts concrete strength, quality, and therefore cost of labour for placing and finishing operations.

Methods of improving workability of concrete: 

• To increase the workbility we have to follow a few steps, they are:
• Increase water-cement ratio
• Using large aggregate
• Using well-rounded and smooth aggregate ratherthan irregular shape.
• By proper mixing time and temperature.
• By using non-porous and saturated aggregate.

The following tests are commonly used to check the workability of concrete, they are

1. Slump test

2. Compaction factor test

3. Kelly ball test

4. Flow test

5. K-Slump test

6. Vee-Bee consistometer test.

 

Reference: American Concrete Institute (ACI) Standard 116R-90 (ACI 1990b)