Environmental Inspection in Singapore

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Environmental Inspection in Singapore
Poon Chiew Tuck
Senior Engineer
Pollution
Control Department National
Environment Agency Singapore
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Introduction

• Pollution Control Department (PCD) enforces laws
  and regulations on environmental pollution
• Organization chart
• PCD implements programmes of inspections,
  surveillance, checks, monitoring, sampling and
  testing

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Environmental Laws

• The Environmental Pollution Control Act (EPCA)
  and its subsidiary regulations are the main
  pollution control laws in Singapore
• The EPCA covers the following
• Industrial air pollution
• Vehicular emission
• Water pollution
• Hazardous wastes
• Hazardous chemicals
• Noise pollution

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Main Features of EPCA

• Pollutive factories must have licence to operate
• Industries have to comply with the stipulated air
  emission standards and trade effluent discharge
  standards
• Pollution control equipment must be working in a
  proper and efficient manner when factory is in
  operation
• PCD has the power to issue notice to any factory
  to take additional measures to prevent pollution

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Inspection Sampling Programme

• Factories are categorized as follows
• Category A factories - those that require
  licence to operate such as oil refineries, power
  stations, chemical plants, steel mill, dye and
  textile factories, electroplating plants and
  those that discharge trade effluent into
  watercourse
• Category B factories - those that can cause some
  degree of pollution such as electronic factories,
  food and beverage factories, petrol stations,
  etc
• Category C factories - those that can minor
  pollution such as general engineering workshops,
  printing industry, etc.

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Inspection Sampling Programme

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Inspection Sampling Programme

• Typical Inspection Tasks
• pH value of discharge (pH 6 9)
• turbidity/colour of discharge
• condition of trade effluent treatment plant
  process
• sufficient chemicals provided
• chemical pumps, stirrers, etc in operation
• condition of air pollution control equipment\
• general housekeeping

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Tools for pH check
Handheld pH meter

• pH test strips

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Inspection Sampling Programme

• Trade Effluent Sampling
• Sample to be representative of discharge
• Deterioration and contamination of samples to be
  avoided
• Sample at the point just before discharge
• Only one sample required per visit
• Parameters to be analysed depend on the raw
  materials and chemicals used in the manufacturing
  process
• Common parameters are BOD, SS and pH for organic
  waste and COD, pH or heavy metals for chemical
  waste. (standards)
• Sample is analysed at outsourced laboratory
  according to Standard Methods for the Examination
  of Water and Wastewater Analysis published by the
  American Water Works Association.

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Trade Effluent Sampling
Sample taken just before point of discharge
discharge point into sewers
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Inspection Sampling Programme

• Air Emission Sampling
• Category A factories and those with fuel burning
  equipment must conduct stack testing at least
  once a year to show compliance with stipulated
  standards
• Common pollutants sampled are Dust, SO2, NOx, CO,
  HCl, Dioxins
• Results submitted to PCD
• Enforcement action taken against offenders that
  exceed stipulated standards
• Factories engage approved testing companies to
  conduct the test
• Approved testing companies must be accredited by
  Singapore Accreditation Council
• US EPA Methods of stack sampling procedures
  commonly used.

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Air Emission Sampling
Conducting air emission sampling at a stack.
Proper test facilities with sampling hole and
standing platform fixture are provided
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Best Practices
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Discharge Control System

• Acidic discharge is highly pollutive and damaging
  to sewerage infrastructure and sewerage workers
• Factories that can discharge acidic trade
  effluent must install continuous pH Monitoring
  System
• The pH Monitoring System shuts off the discharge
  valve when pH falls outside the 6-9 range
• Chart recordings of the pH values are submitted
  to PCD monthly for checking
• The control panel housing the chart recorder is
  sealed to prevent tampering

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Discharge Control System with Continuous pH
Monitoring System
Control Panel
Gate Valve
Chart Recorder inside Control Panel
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Smoke Density Meter

• Smoke is a good indicator of whether combustion
  process is efficient and pollution from stacks
• Smoke density meter installed on stack to monitor
  for dark smoke emission
• Results submitted to PCD monthly for checking
• Enforcement action taken against offenders that
  exceed the stipulated standards

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Smoke Density Meter
flue gas
Chart recorder
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Human Resource Practices

• Regular staff reshuffling exercise ie job
  rotation
• Staff transfer within catchment teams/sections
• Minimize development of unhealthy relations
  between officers and potential offenders
• Supports career development
• Emphasis on continuous training
• At least 40 hours per officer per year

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Typical Problems

• Main issues with discharge from textile and dye
  industries are BOD and colour of the discharge
• Discharge bypassing treatment process
• Other industries
• low, acidic pH (electroplating)
• heavy metals (electroplating, galvanising)
• high BOD (food beverage, refineries)
• high COD (petrochemical plants, spent oil
  chemicals collectors)
• high oil grease (engineering workshop,
  refineries)

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Solid Waste

• No major issue with solid waste from textile and
  dye industries
• Solid waste generated is disposed of together
  with general waste at refuse incineration plants
• Managing hazardous waste (such as spent oil and
  chemicals) from other industries is more
  challenging
• only licence collectors with proper facilities
  are allowed to treat and disposed of hazardous
  waste.

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Introduction to Waste Treatment Technologies

• Waste water treatment types
• Physical treatment
• Chemical treatment
• Biological treatment
• Thermal treatment

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Physical Treatment

• Sedimentation/settling
• Filtration
• Oil/Water separation

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Sedimentation/settling

• Removal of suspended solids by allowing
  sufficient time for the solids to settle by
  gravitational force to the bottom of the tank.
  Clarified effluent overflows out from the top of
  the tank.

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Filtration

• Removal of solids by passing the waste water
  through a granular filter media such as sand and
  gravel or filter membrane such as fibre, cloth or
  cotton wool.

Inlet
xxx
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Oil/Water Separation

• Oil interceptor an underground tank which
  has 3 separate compartments interconnected by
  T-pipes. As oil is lighter than water, it will
  rise to the top, allowing clean water to flow
  out. Commonly used in vehicle workshops, petrol
  stations and oil storage areas.

Inlet
Outlet
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Oil/Water Separation

• API interceptor Commonly used in big
  installations such as oil refineries and oil
  storage terminals. Oil and scums on the surface
  are skimmed off mechanically. Silt and solids
  will settle to the bottom.

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Chemical Treatment

• Neutralisation
• Precipitation
• Coagulation/flocculation

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Neutralisation

• The term is used to refer to the adjustment of
  pH in the effluent by introduction of chemicals.
  When the pH is lower than 7, the solution is
  acidic. Alkaline chemical such as caustic soda or
  sodium hydroxide can be added to neutralize it to
  pH 7. Similarly, when the pH is higher than
  7(alkaline), acidic chemical such as sulphuric
  acid is added to neutralize it to pH 7.

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Precipitation

• Precipitation is a process of removing heavy
  metals from the electroplating waste water
  through pH adjustement to form metallic
  hydroxides. Each metal salt has its own pH level
  for precipitation to take place.

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Coagulation/Flocculation

• In untreated condition, suspended particles are
  stabilised by negative electrical charges on
  their surfaces, causing them to repel each other
  and prevent formation of large masses (flocs). By
  introducing coagulant chemicals into the
  effluent, the molecules that carries positive
  (ve) charges will neutralize the particles
  surface electrical charges (-ve) and cause them
  to destabilise. The particles will then be able
  to agglomerate (bond) with each other whenever
  they collide.
• Flocculation is the formation of flocs. It is
  the process of bridging the flocculant chemical
  between the agglomerated particles to form larger
  and settleable flocs. Flocculation will take
  place when continuous dosing of flocculant
  chemical into coagulated particles with the aid
  of constant slow movement of the waste water by
  means of stirrer

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Biological Treatment

• Trickling/biological filters
• Activated Sludge process

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Trickling/biological filters

• It is a device used for bringing the settled
  wastewater into contact with the micro-organism
  and promote its growth on a filter media. The
  organic matter present in the settled wastewater
  serves as food for the aerobic micro-organism
  which live on the filter media surface

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Activated Sludge Process

• This is similarly to the trickling filter
  process except that constant air supply is
  introduced into the waste water to promote
  bacteria growth. The air supply is provided
  either through mechanical impellers or diffused
  air from the bottom.

Mechanical impeller
Diffused air
Mechanical aeration
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Thermal Treatment

• Incineration
• Typically used when for treating wastes which are
  hazardous, pollutive, flammable or biohazardous
  usually at high temperatures

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Useful Websites
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Thank You