waste treatment

WASTE TREATMENT

Prepared by: Elijah M. AvanteMS Microbiology 2012-98147

WHAT IS WASTEWATER?

domestic sewage or liquid industrial waste that cannot be discarded in untreated form into lakes or streams due to public health

Industrial sources: –dairy, food, pharmaceutical etc. (~1500 BOD units)

Domestic sources: – Form households and non-industrial businesses (~200 BOD units) (Madigan et al.,2012)

WASTEWATER TREATMENT

majority of wastes generated by humankind were disposed of directly into the environment. (Waites et al., 2001)

employs physical and chemical methods as well as industrial-scale use of microorganisms. (Madigan et al., 2012)

WHY TREAT WASTEWATER?

So that they can be safely discharged directly into the environment (rendering them chemically and biologically harmless) (Waites et al., 2001)

(http://musicminers.org/)

SEWAGE

liquid effluent contaminated with human or animal fecal materials

may also contain potentially harmful inorganic and organic compounds as well as pathogenic microorganisms (Waites

et al., 2001)

(waterdesalinationplants.com) 

On average, each person in the United States uses 100–200 gallons of water every day for washing, cooking, drinking, and sanitation. (Madigan et al.,2012)

(http://sadmanstongue.com)

SCREENING FOR SUITABLE TREATMENT Before establishing the most suitable method

for treating and disposing of any given pollutant, analytical methods are required to assess the polluting strength of the waste.

Biochemical Oxygen Demand (BOD) Chemical Oxygen Demand (COD) Total Organic Carbon (TOC) Total Suspended Solids (TSS) Total Solids (TS) (Waites et al.,2001)

BIOCHEMICAL OXYGEN DEMAND (BOD) The efficiency of treatment is

expressed in terms of a reduction in the biochemical oxygen demand (BOD)

High levels of organic and inorganic materials in the wastewater result in a high BOD (Madigan et al.,2012)

BOD

The BOD test estimates the amount of oxygen required by aerobic microorganisms to oxidize biodegradable material in polluted waste-waters over a fixed period of time (normally 5 days), at constant temperature (20°C) in the dark (prevents the possibility of photosynthetic (algae) production of DO) (Waites et al.,2001)

BOD

“Seed" bacteria

bacteria from receiving waters (rivers, ponds)

soil suspensions raw wastewater *most commonly used

lypholyzed commercial seed

BIOLOGICAL OXYGEN DEMAND (BOD)

(http://www.hach.com)

CHEMICAL OXYGEN DEMAND (COD)

Because of the drawback of BOD test having a long incubation period required Chemical Oxygen Demand test was developed

This determines the amount of oxygen required to chemically oxidize any oxidizable material present in a wastewater

COD Each test involves adding a known volume of

sample to a mixture of oxygen-rich potassium dichromate and concentrated sulfuric acid.

This is refluxed for 2–4h and the residual concentration of dichromate is determined by titration with ferrous sulfate or ferrous ammonium sulfate.

The concentration of oxidizable compounds is proportional to the potassium dichromate utilized and the results are expressed in milligrams of oxygen per liter.

COD

(www.news.thomasnet.com)

COD VS BOD

BOD only measures the amount of oxygen consumed by microbial oxidation and is most relevant to waters rich in organic matter.

COD and BOD do not necessarily measure the same types of oxygen consumption. COD does not measure the oxygen-consuming potential

associated with certain dissolved organic compounds such as acetate. However, acetate can be metabolized by microorganisms and would therefore be detected in an assay of BOD.

In contrast, the oxygen-consuming potential of cellulose is not measured during a short-term BOD assay, but it is measured during a COD test.

(http://science.jrank.org)

The overall efficiency is in the order TDS < COD < TSS < BOD in Mailasandra STP while in Nagasandra STP, it is TDS < COD < BOD < TSS.

COD VS BOD

COD values are always higher than the BOD values. Because COD includes both biodegradbale and non-biodegradable substances whereas BOD contains only bio-degradable.

BOD analysis is performed mainly to satisfy permit requirements.

COD measured provides a quantitive estimate of everything currently in the waste stream that can be oxidized. *thereby permitting closer operational control of the treatment process (Abdul et al., 2012)

WASTE TREATMENT PROCESSES

The aerobic/anaerobic self-purification sequence that occurs when organic matter is added to lakes and rivers can be carried out under controlled conditions in which natural processes are intensified (Willey et al.,2008)

PRIMARY TREATMENT

Physically removes 20 to 30% of the BOD that is present in particulate form.

In this treatment, particulate material is removed by screening, precipitation of small particulates, and settling in basins or tanks.

The resulting solid material is usually called sludge (Willey et al.,2008)

SECONDARY TREATMENT

promotes the biological transformation of dissolved organic matter to microbial biomass and carbon dioxide.

About 90 to 95% of the BOD and many bacterial pathogens are removed by this process (Willey et al., 2008)

SECONDARY ANAEROBIC WASTEWATER TREATMENT

a series of degradative and fermentative reactions carried out by various prokaryotes under anoxic conditions.

used to treat wastewater containing large quantities of insoluble organic matter (and therefore having a very high BOD) such as fiber and cellulose waste from food and dairy plants (Madigan et al.,2012)

SECONDARY ANAEROBIC WASTEWATER TREATMENT

(Madigan,2012)

SECONDARY ANAEROBIC WASTEWATER TREATMENT

(Madigan et al.,2012)

(Madigan et al.,2012)

SECONDARY AEROBIC WASTEWATER TREATMENT

uses oxidative degradation reactions carried out by microorganisms under aerobic conditions to treat wastewater containing low levels of organic materials

wastewaters that originate from residential sources can be treated efficiently using only aerobic treatment (Madigan et al.,2012)

SECONDARY AEROBIC WASTEWATER TREATMENT

These systems are of two types

Trickling Filter System - sewage is sprayed over a bed of rocks (coated with a slimy film of aerobic organisms such as Sphaerotilus and Beggiatoa) and removes about 80% of the organic matter in the water

Activated Sludge System - the effluent from primary treatment is constantly agitated, aerated, and added to solid material remaining from earlier water treatment (Black,2012)

TRICKLING FILTER SYSTEM

(Willey et al.,2008)

(ETI,1998)

AERATION

The underdrain system is designed to meet two objectives: collect treated wastewater create a plenum that allows for the

transfer of air throughout the trickling filter media. (Daigger & Boltz,2011)

AERATION

The vertical flow of air through trickling filter media can be induced by mechanical ventilation or natural air draft. Mechanical ventilation enhances controls

airflow with low-pressure fans that continuously circulate air throughout the trickling filter.

Adequate underdrain and effluent channel permits free airflow. (vent stacks ventilating manholes or louvers on the sidewall of the tower) (Daigger & Boltz,2011)

SLOUGHING

As the layer thickens (with microbial growth), oxygen cannot penetrate to the media face, and anaerobic organisms develop. As the biological film continues to grow, the microorganisms next to the surface lose their ability to cling to the media, and a portion of the slime layer falls off the filter. This is known as sloughing and is the main source of solids picked up by the underdrain system. (ETI,199

8)

BIOMASS CONTROL

Mechanical removal Backwashing can be applied only with no-fluidizing

packing. After any mechanical removal, biotrickling filters require some days to reach the elimination capacities they had before the treatment. *Simple and effective but also very expensive

Chemical Removal First attempts were carried out with NaOH(0.1M)

solution in toluene degrading bioreactor NaOH, sodium dodecylsulphate, NaN3, NaClO, H2O2,

ethanol, saturated iodine, NH3 and HCO are the chemicals often use in chemical treatment. Many of these attempts completely deactivated the biomass. NaClO seems to be the most promising chemical.(Della

Vedova,2008)

ACTIVATED SLUDGE SYSTEM

(Willey et al.,2008)

AERATION

Supplying the required oxygen to the organisms to grow and providing optimum contact between the dissolved and suspended organic matter and the microorganisms.

Mechanical aerators physically splash the wastewater into the atmosphere above the tank and create turbulence assuring effective wastewater mixing. brushes, blades or propellers that introduce air from the atmosphere. Surface aerators float at the surface or are mounted on supports in or above the basin. Mechanical aerators tend to incur lower installation and maintenance costs. (Pipeline,2003)

AERATION

A diffused air system introduces compressed air through a perforated membrane into the wastewater. Diffusers are classified by the physical characteristics of the equipment, or by the size of the air bubble. The choice of bubble size, diffuser type, and diffuser placement can have a great effect on the efficiency of the aeration process.

(Pipeline,2003)

FLOC FORMED BY AN ACTIVATED SLUDGE SYSTEM

(Case et al.,2011)

SOME MICROORGANISMS INVOLVE IN AEROBIC WASTE TREATMENT

Bodo sp. Vorticella sp. Actinophrys sp. Euplotes sp. Nematoda Mastigophora sp. Zoogloea sp.

*The organisms that can be found in a trickling filter do not differ much from the ones found in activated sludge

BULKING

Occasionally, the sludge will float rather than settle out and this will result into bulking

Organic matter in the floc flows out with the discharge effluent, resulting in local pollution. Sphaerotilus natans Nocardia sp.

(Case et al.,2011)

BULKING

Here are several methods on treating bulking on the activated sludge system. Chlorination - chlorine and hydrogen Flushing – high water pressure to clean the

tank Distillation and pH Titration Method –

treating septicity *Adjust parameters for to prevent bulking

(Richard,2003)

DIFFERENT PROCESS FOR WASTE TREATMENT

Fixed film processes — microorganisms are held on a surface, the fixed film, which may be mobile or stationary with wastewater flowing past the surface/media. These processes are designed to actively contact the biofilm with the wastewater and with oxygen, when needed

Suspended growth processes — biomass is freely suspended in the wastewater and is mixed and can be aerated by a variety of devices that transfer oxygen to the bioreactor con- tents (Schultz,200

5)

FIXED-FILM OPTIONS

Biotowers (trickling filters)

Rotating biological contactors

Submerged biological contactors

(Schultz,2005)

ROTATING BIOLOGICAL CONTACTORS

consist of vertically arranged, plastic media on a horizontal, rotating shaft

biomass- coated media are alternately exposed to wastewater and atmospheric oxygen as the shaft slowly rotates at 1–1.5 rpm

(Schultz,2005)

ROTATING BIOLOGICAL CONTACTORS

(Schultz,2005)

SUBMERGED BIOLOGICAL CONTACTORS

(www.sswm.info)

SUBMERGED BIOLOGICAL CONTACTORS operate at nearly 90% submergence

with coarse-bubble diffused aeration providing a means of both aeration and motive force for rotation

SUSPENDED-GROWTH OPTIONS

Diffused aeration

Jet aeration

(Schultz,2005)

DIFFUSED AERATION

(www.brightwaterfli.com)

(www.ecosafeindia.com)

JET AERATION

(Schultz,2005)

DIFFUSED AERATOR

Diffused aerators add air to wastewater, increasing dissolved oxygen content and supplying microorganisms with oxygen necessary for aerobic biological treatment

(Schultz,2005)

JET AERATION

It is designed to provide required aeration as well as maintain suspension of biological solids, with the flexibility to either aerate or mix independently without the need for additional equipment

When air is not available pumps provide the required mixing action

Since jet aeration requires no moving parts in the basin, the system offers long life with no in-basin routine maintenance required

(Schultz,2005)

(Black,2012)

SLUDGE DIGESTION

Primary sludge - accumulates in primary sedimentation tanks

Sludge - accumulates in activated sludge and in trickling filter secondary treatments Undergo further treatment in a anaerobic

sludge digester The process of sludge digestion is carried

out in large tanks from which oxygen is almost completely excluded

(Case et al.,2011)

SLUDGE DIGESTION

There are essentially three stages:

The first stage is the production of carbon dioxide and organic acids from anaerobic fermentation of the sludge by various anaerobic and facultatively anaerobic microorganisms.

In the second stage, the organic acids are metabolized to form hydrogen and carbon dioxide, as well as organic acids such as acetic acid.

These products are the raw materials for a third stage, in which the methane-producing bacteria produce methane (CH4).

(Case et al.,2011)

(Case et al.,2011)

SLUDGE DIGESTION

After anaerobic digestion is completed, large amounts of undigested sludge still remain.

To reduce its volume, this sludge is pumped to shallow drying beds or water-extracting filters. can be used for landfill, as a soil conditioner or

fertilizer (biosolids) Classified as class A & B which means doesn’t

contain any pathogen and the one that has and needs to be treated because of the presence of pathogens

(Case et al.,2011)

DRYING BED

(http://www.defence.gov.au)

TERTIARY TREATMENT

Fine sand and charcoal are used in filtration and involves physical and chemical methods

Chlorine or Ultraviolet Light is used to destroy any remaining organisms (Black,2012)

(Black,2012)

MICROBIAL FUEL CELLS Directly generating electricity from organic

matter in wastewater, while simultaneously treating the wastewater

Electrons released by bacterial oxidation of the organic matter are transferred through the external circuit to the cathode where they combine with oxygen to form water.

*Treatment was examined here in terms of maximum power densities, Coulombic efficiencies (CEs), and chemical oxygen demand (COD)

MFC

(http://www.sciencedaily.com)

MFC

In the first step of the MFC, an anode respiring bacterium breaks down the organic waste to carbon dioxide and transfers the electrons released to the anode.

Next, the electrons travel from the anode, through an external circuit to generate electrical energy.

Finally, the electrons complete the circuit by traveling to the cathode, where they are taken up by oxygen and hydrogen ions to form water.

MFC

At COD concentrations of 200 and 350 mg/L, the maximum power densities with the brewery wastewater were 53 and 63 mW/m2, respectively.

MEDICAL WASTE

Covers all wastes produced in health-care or diagnostic activities

75 % to 90 % of hospital wastes are similar to household refuse

(International Committee of the Red Cross, 2011)

(International Committee of the Red Cross, 2011)

(International Committee of the Red Cross, 2011)

METHODS OF TREATING MEDICAL WASTES Incineration Chemical Disinfection Autoclaving Needle Extraction or

Destruction Shredders Encapsulation Disposal in a sanitary

landfill or waste burial pit

(www.health.ny.gov)

(International Committee of the Red Cross, 2011)

METHODS OF TREATING MEDICAL WASTES chemical: addition of disinfectants (chlorine

dioxide, sodium hypochlorite, peracetic acid, ozone, alkaline hydrolysis

irradiation: UV rays, electron beams biological: enzymes Thermal:

low temperatures (100° to 180°C): vapour (autoclave, micro-waves) or hot air (convection, combustion, infrared heat)

high temperatures (200° to over 1000°C): incineration (combustion, pyrolysis and/or gasification);

METHODS OF TREATING MEDICAL WASTES mechanical processes: shredding (a

process which does not decontaminate the waste)

encapsulation (or solidification) of sharps

burial: sanitary landfills, trenches, pits.

WASTE MANAGEMENT IN PHILIPPINES

Republic Act (RA) No. 9003 (“The Ecological Solid Waste Management Act of 2000”)

Department of Environment and Natural Resources (DENR) Administrative Order (DAO) No. 2001-34, the Implementing Rules and Regulations (IRR) of RA 9003. (Manila Standard

Today,2005)

LA MESA TREATMENT PLANT

(http://www.mayniladwater.com.ph)

PUTATAN TREATMENT PLANT

(http://www.mayniladwater.com.ph)

DENR & DOH

Toxic Substances, Hazardous Waste, and Nuclear Waste Control Act of 1990 [Republic Act 6969]

Ecological Solid Waste Management Act of 2000 [Republic Act 9003]

Clean Water Act of 2004 [Republic Act 9275]

Hospital Licensure Act [Republic Act 4226] (Manila Standard Today,2005)

(http://www.pwp.org.ph)

REFERENCES Waites, M.J, Morgan, N.L. Rockey, J.S. & Higton, G. (2001). Industrial Microbiology: An

Introduction. USA: Blackwell Science Ltd.

Madigan, M.T., Martinko, J.M., Stah, D.A. & Clark (2012). Brock Biology of Microorganism. San Francisco, CA: Madigan Education, Inc.

Willey, J.M., Sherwood, L.M. & Woolverton, C.J. (2008). Prescott,Harley, and Klein’s Microbiology. New York: The McGraw-Hill Companies, Inc.

Robinson, T., & Singh Nigam (2008). Remediation of Textile Dye Waste Water using a white-Rot Fungus Bjerkandera adusta. Applied Biochemical Biotechnology 15: 618-628.

Black, J.G. (2012). Microbiology: Principles and Explorations. USA: John Wiley & Sons, Inc.

Abdulkareem, A.S. (2004). Modeling of Microbial Growth in a Wastewater Treatment Plant: A Case Study of Textile Industry in Kaduna, Nigeria. AU J.T. 8(1): 45-54.

Davies, P.S. (2005). The Biological Basis of Wastewater Treatment. Kelvin Campus, West of Scotland Science Park Glasgow G20 0SP, UK Strathkelvin Instruments Ltd

International Committee of the Red Cross (2011). Medical Waste Management. shop@icrc.org www.icrc.org

Gozun, E.G. (2003) Handbook On The Ecological Solid Waste Management Act Of 2000 (RA 9003) and Its Implementing Rules and Regulations (IRR). Manila: The Philippine Environmental Governance Program, Department of Environment and Natural Resources.