Environmental Engineering

Environmental Engineering

Environmental Engineering is manifest by sound engineering thought and practice in the solution of problems of environmental sanitation, notably in the provision of safe, palatable, and ample public water supplies; the proper disposal of or recycle of waste water and solid waste; the adequate drainage of urban and rural areas for proper sanitation; and the control of water, soil and atmospheric pollution, and the social and environmental impact of these solutions. Furthermore it is concerned with engineering problems in the field of public health, such as control of arthropod-borne diseases, the elimination of industrial health hazards, and the provision of adequate sanitation in urban rural and recreational areas, and the effect of technological advances on the environment.


Environmental Management System of Greenlab ECL

Compilation of EMS for Industries: We can compile sustainable EMS for DoE defined Orange & Red category industries

Obtainment of ISO certificates: We can support industries in obtaining ISO 9000, 14001/10, OHSAS 18001 certificates.

Environmental Impact Assessment (EIA): IEE and EIA for DoE defined Orange-B and Red Category Industries.

Environmental impact assessment is an assessment of the possible positive or negative impact that a proposed project may have on the environment, together consisting of the natural, social and economic aspects. The two main considerations are:

  • Scientific - to check the accuracy of predictions and explain errors.
  • Management- to assess the success of mitigation in reducing impacts.

The goal of EIA

The goal of all environmental assessments is to protect the environment by ensuring that only environmentally sound projects are designed and implemented. In EIA, positive and negative impacts are identified and either project designs are altered or mitigation measures are developed to lessen or alleviate negative ones. Public participation is central to the process and should take place at all stages of an EIA. The EIA involves an integrated assessment of the impacts of a project or plan on both natural and human environments. It focuses on linkages among the physical-chemical, biological, social and economic components of the environment. The important environmental components on which impacts will be assessed are: Water resources - Surface water, Ground water, Water quality, Water transportation; Land resources - Land types, Land use, Soils, Agriculture; Biological resources - Capture fisheries, Culture fisheries, Forest and Homestead vegetation, Wetlands, Wildlife; and Human resources - Socio-economic, Public health, Hazard and risk assessment. The guidelines constitute simple procedures and formats to guide Initial Environmental Examination (IEE) and Environmental Impact Assessment (EIA) of proposed projects and draw up plans for environmental management. The guidelines may also be used to conduct IEE and EIA of ongoing and implemented projects to identify potential negative impacts and to design environmental protection measures and appropriate monitoring programmes.


Social Impact Assessment:

Identify Social Impact Assessment Variables

Social impact assessment variables point to measurable change in human population, communities, and social relationships resulting from a development project or policy change. After research on local community change, rural industrialization, reservoir and highway development, natural resource development, and social change in general, we suggest a list of social variables under the general headings of:

1. Population Characteristics

2. Community and Institutional Structures

3. Political and Social Resources

4. Individual and Family Changes

5. Community Resources



Social Impact Assessment Variables


Waste Water Treatment Scheme

Coarse screens or bar racks  :

(1) removes large objects, rags, debris ; (2) protects downstream pumps, valves, pipelines ; (3) cleaning may be accomplished manually or mechanically ; (4) mechanically cleaned bar racks typically used instead of coarse manually cleaned screens ; (5) bar rack is inclined to facilitate , cleaning ; (6) approach velocities should ensure self-cleaning, but not dislodge solids.

Aerated Grit Chamber:

Inert dense material such as sand, broken glass, slit and pebbles, etc is called grit. If these materials are not removed from the waste water they abrade pumps and other mechanical devices, causing undue wear. In addition they have a tendency to settle in corners and bends, reducing flow capacity and ultimately, clogging pipes and channels. In aerated grit chamber the shearing action of the bubbles is supposed to strip the inert grit of much of the organic material that adheres to its surface.


Equalization is not a treatment process but a technique that can be used to improve the effectiveness of both secondary and advanced wastewater treatment processes. Equalization is usually achieved by constructing large basin that collect and store the waste water flow from which the waste water is pumped to the treatment plant at a constant rate with a average temperature. Addition of aeration at equalization tank also reduces Temperature, TSS, BOD and COD.


Flocculation is a process where colloids come out of suspension in the form of floc or flakes. The action differs from precipitation in that, prior to flocculation, colloids are merely suspended in a liquid and not actually dissolved in a solution. In the flocculated system there is no formation of a cake since all the flocs are in the suspension. Flocculants, or flocculating agents (also known as flocking agents), are chemicals that promote flocculation by causing colloids and other suspended particles in liquids to aggregate, forming a floc. Flocculants are used in water treatment processes to improve the sedimentation or filterability of small particles. Many flocculants are multivalent cations such as aluminum, iron, calcium or magnesium. These positively charged molecules interact with negatively charged particles and molecules to reduce the barriers to aggregation. In addition, many of these chemicals, under appropriate PH and other conditions such as temperature and salinity, react with water to form insoluble hydroxides which, upon precipitating, link together to form long chains or meshes, physically trapping small particles into the larger floc.

10 Ca2+ + 6 PO43- + 2 OH- ↔ Ca10(PO4)*6(OH)2 ↓

Ca(HCO3)2 + Ca(OH)2 à 2CaCO3 ↓+ 2H2O

Al3+ + HnPO43-n ↔ AlPO4 + nH+

Fe3+ + HnPO43-n ↔ FePO4 + nH+

Clarifier (LAMELLA)/Sedimentation Tank:

¨  Removal of SS, BOD and COD about 50-55% at primary clarification.

¨  Reduces space but surface area increases.

¨  Solid Particle is settled easily by Cross flow through the inclined surface

¨  Less Power requirement

¨  Easily sludge removed due to downward flow into hopper.

¨  More effective than normal clarifier.

Fluidized Media Reactor (FMR):

The FMR technology is a single tank design unit; incorporating

  • A bar screen,
  • A specially designed tank with synthetic media,
  • A lamella settler, and
  • A chlorine contact tank.


¨  The main objective of adding this media is to make available more surface area for bacteria to grow on.

¨  The FMR media material allows biomass concentration of 20 – 40 Kgs/m3 material.

¨  High concentration of biomass enables reduction of aeration tank and in turn reduction in overall cost.

¨  As all units are placed inside a single tank, it saves space and also increases operational ease, Increases the specific volumetric capacity of activated sludge tanks, Controls biomass activity.

¨  Reduced power and operating costs

¨  No Sludge recycle

¨  No moving parts, less maintenance

Activated sludge process/Aeration:

Activated sludge process derives its name from the biological mass formed when air is continuously injected into the wastewater. In this process microorganisms are mixed thoroughly with the organics under conditions that stimulate their growth through use of the organic food. As the microorganisms grow and are mixed by the agitation of the air, the individual organisms clump together to form an active mass of microbes (biological floc) called activated sludge.

C5H7NO2+5O2= 5CO2+2H­2O+HN3+Energy

The technique consists of 3 different systems:

  1. A biological reactor - using a suitable biomass for settling,
  2. An aeration system to provide the necessary oxygen for the biomass,
  3. A separation facility, where the purified water is separated from the biomass through settling.

Adsorption (PAC, Natural Adsorbent)

Many industrial wastes contains organic, which are refractory and which are difficult or impossible to remove by conventional biological- treatment processes.  These materials can frequently be removed by adsorption on an active solid surface. When a solid- fluid containing system of operation is used to treat a fluid stream on an industrial scale, one of the following characteristics has usually been responsible for its selection as the most economical methods for treatment.

1.       High selectivity of the adsorbent.

2.       High concentrating power of  the adsorbent, related to the   Selectivity

3.       Chemical instability of the adsorb ate, restricting it to temperatures  unsuited for other separation

4.       Fluctuation or intermittent supply of the fluid feeds.

5.       Less space need & Lower capital investment.

6.        Simple design & Easy operation of the equipment.

7.        Efficient removal of organic waste constituents.

Advanced Industrial Wastewater Treatment

Recovery and reuse of process water in industrial treatment systems requires a new technological strategy based on the separation of process water from the process chemistry. These advanced industrial wastewater treatment system combine traditional off-the-shelf technologies such as

1.    Ion-Exchange

2.    Membrane bioreactor (MBR)

3.    Ultra filtration

4.    Reverse Osmosis

5.    Micro filtration

8.    Granular Media Filters

9.    Trickling Filter System

10. Aerobic Digestion system

11. Chlorination/Disinfection

Utility Management

Water supply, wastewater, solid waste and energy are services traditionally provided by the public sector. Increasing pressure towards making these services operate in more self-sustaining and reliable ways is being placed largely on the utilities responsible for managing these services. In light of this, service providers are forced to become more autonomous, transparent and accountable. Undeniably, this process poses major challenges to all stakeholders.

Consultancy services covering all aspects of utility management in the water, wastewater, solid waste, and energy sectors. We can provide specialist services in the following areas:

  • Strategy development, incl. missions, legal framework, organization principles, ownership, technical, marketing.
  • Market analysis and institutional assessment, legal, financial, technical, environmental and HRD issues.
  • Business Plans, incl. investment planning, budgeting, institutional and HRD planning, marketing plans.
  • Implementation, incl. management, organizational issues, financial management, international auditing, procedures manuals, levels of service, HRD, IT systems.
  • Operations, incl. operation and maintenance planning, O&M manuals, equipment inventories, MIS, training, customer relations.
  • Exit strategies, incl. extension of existing arrangements, transfer back to public ownership, progression to full privatization.

Disaster Risk Management for Natural Disasters (Flood, Drought, Landslide, Cyclones, etc.)


Risk Assessment:

The concept of risk and hazard are inextricably intertwined. Hazard implies a probability of adverse effects in a particular situation. Risk is a measure of the probability. In some instances the measure is subjective or perceived risk. In some instances actual data may be used to estimate the risk. An attempt has been made to bring more rigors to the risk assessment, or rapidly risk assessment. The use of the results of a risk assessment to make policy decision is called risk management.

Data collection and Evaluation- Data collection and evaluation includes gathering and analyzing site-specific data relevant to human health concern for the purpose of identifying substances of major interest. This step includes gathering background and site information as well as the preliminary identification of potential human exposure through sampling, and development of a sample collection strategy.

Greenlab ECL collects and manages the background information and it is important to identify the followings:

1.    Possible contaminates on the site.

2.    Concentrations of the contaminants in key sources and media of interest, characteristics of sources, and information related to the chemical’s release potential and

3.    Characteristics of the environmental setting that could affect the fate, transport, and persistence of the contaminants.


Disaster Management


ü  Disaster Risk Management for Natural Disasters (Flood, Drought, Landslide, Cyclones, etc.)

ü  Vulnerability and Risk Assessment (Environmental and Social Perspectives)

ü  Food Security in Coastal Area of Bangladesh



Env. Analysis & Monitoring



ü  We can conduct environmental auditing for the Manufacturing/processing industries to ensure parties

ü  Compliance with applicable environmental requirements.

ü  Environmental Auditing is essential for achieving ISO certificates.



Remote Sensing & GIS


ü  Detailed Land use Mapping

ü  Site Specific Map Compilation

ü  GIS database compilation

ü  GPS & DGPS Survey

ü  High Resolution Image Acquisition

ü  Mapping and cartographic support to developmental projects



Ecology & Biodiversity

ü  Landscape Planning

ü  Ecological Survey

ü  Biodiversity Assessment

ü  Environmental Support in Conservation Projects

ü  Environmental Assistance in Protection of Natural Parks/Game Reserve/Protected Area and declared ECAs






Published on: Wednesday, 29 January 2014, 11:44 am   ▪   Last update: Sunday, 13 August 2017, 10:52 am   ▪   Total View of this Page: 1444

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