Integrated green technologies for MSW

Prof. Dr. Mamdouh Abdel-SabourHead of Environmental consultancy

(IIESC)

Some technical and strategic solutions for a green- environmental-friendly waste management in SA

Solid waste management problems

1. SA is facing a great challenges for waste management due to the fast demographic and industrial growth, which left the country with accumulative amount of generated waste that needs to be managed in the most cost-effective, sustainable and green.

“Today, SA accounts for 4.5 hector of ecological footprint per person, or roughly twice the world average,” (Al Fadl 2010).

Traditional MSW management became more expensive and less convenient.

Solid waste management problems

3. MSW management Strategy should emphases largely on sustainable life cycle development.

2. The conventional waste handling method: Causes people inconvenience of handling waste, Unpleasant odor, Harmful pests and diseases, Disagreeable from the surroundings Negative environmental impacts

Potential worries Dust and Odor emmission Litter Noise Visual Impacts

The objective is : To reduce generated waste, Improve its management, Increase recycling, Achieve energy recovery and Reduce landfilling (Zero landfill

approach).

The crucial need to improve MSW collection systems

Most of the generated MSW are disposed in landfill Wasting a recyclables resources, losses of its energy content, Increasing adverse impact on the environment Ground water pollution and Gaseous emissions which cause the global warming problem. High cost for the municipalities/Inefficient consequence

RECOMMENDED APPROACHES TO WASTE MANAGEMENT

Processing / Treatment should be : Technically sound Financially viable Environmental friendly Easy to operate & maintain by local community Long term sustainability

1) Transfer Station

It helps to reduce collection costs. Costs should be less than transportation to landfill directly

Collection vehicles spend less time driving to/from disposal site and more time on route

Transfer station become feasible when the travel distance to the landfill is 20-30 miles or more (one way).

It Can provide processing point for recyclables or other materials

Transfer station should meets one of the following criteria: Municipality with population < 50,000 or Locality with

population < 85,000 Facility that transfer < 125 tons per day

The primary reason for using a transfer station is to reduce the cost of transporting waste to disposal facilities.

Transfer station could be categorized as:

New green design Vertical waste transfer station

Factors affecting the design of the transfer station site include: Waste stream demands Material types accepted Customer types Traffic flow within the transfer

station

The silos are made of durable material and are able to withstand heavy compacting force, also due to their round shape. The silos are equipped with a leachate drainage system.

Cost Savings:A report about Vertical operating Waste Transfer Station compared to direct transfer by Collection Trucks ( 500 ton/day-Transfer Station located 35km from collection points

Direct haul to landfill vs. long haul via transfer station

2 )MSW characterization.Component of generated MSW

Mixed waste is very difficult to manage and process.

Hazardous waste & medical waste in SA

The private sector of widely varying sizes and capabilities can supplement the knowledge and capacity of the local authority to implement advanced recycling, recovery, and disposal technologies.

For new town and commercial area

3) Under ground vacuum MSW collection systemUrban cities continue to expand to areas with difficult accessibility, posing a challenge for efficient waste collection.

Benefit of Recycling

SORTING PLANT (MRF)

MRF and Waste to energy

Thermal treatment Types• Incineration (complete oxidation)

Mass Burn Refuse Derived Fuel (RDF)

• Pyrolysis• Gasification• Plasma arc (advanced thermal

conversion)

What is the waste advanced thermal technologies?

A Waste-to-Energy Incinerator with Pollution Controls

One tonne of waste creates 3.5 MW of energy during incineration (eq. to 300 kg of fuel oil) powers 70 homes

Air Pollution Control• Remove certain waste components• Good Combustion Practices• Emission Control DevicesElectrostatic PrecipitatorBag-housesAcid Gas Scrubbers

Wet scrubberDry scrubberChemicals added in slurry to neutralize acids

Activated CarbonSelective Non-catalytic Reduction

Schematic Presentation of Bottom Ash Treatment

1. Construction fill2. Road construction3. Landfill daily cover 4. Cement block production5. Treatment of acid mine drainage

Ash Reuse Options Bottom Ash – recovered from combustion chamber Heat Recovery Ash – collected in the heat recovery

system (boiler, economizer, superheater) Fly Ash – Particulate matter removed prior to

sorbents Air Pollution Control Residues – usually combined

with fly ash

Pyrolysis

Thermal degradation of carbonaceous materialsLower temperature than gasification (750 – 1500oF)Absence or limited oxygenProducts are oils and gas, solid charPyrolysis oil used for (after post-treatment):

liquid fuels, chemicals, adhesives, and other products.

Pyrolysis has proved capabilities to transform biomass and waste material of low-energy density into bio-oil of high-energy density and recover higher value chemicals.

Paper cups used as coffee or cold drinks cups are accumulating as wastes on the earth surface at a rapid rate. Considering only America, 14.4 million disposable paper cups are used for drinking coffee each year. Placed end-to end, these cups would wrap around Earth 55 times and weigh around 900 million pounds.

Pyrolysis for Ethanol Example: Ethanol plant

Construction on Fulcrum Bio-energy municipal solid waste to ethanol plant, Sierra Bio-Fuels, started in 2008. Located in the Tahoe-Reno Industrial Center, in the City of McCarran, Storey County, Nevada, the plant convert 90,000 tons of MSW into 10.5 million gallons of ethanol per year.

(http://www.thermoselect.com/index.cfm )

Recovers a synthesis gas, utilizable glass-like minerals, metals rich in iron and sulfur from municipal solid waste, commercial waste, industrial waste and hazardous waste

High temperature gasification of the organic waste constituents and direct fusion of the inorganic components.

Water, salt and zinc concentrate are produced as usable raw materials during the process water treatment.

No ashes, slag or filter dusts

100,000 tpd plant in Japan operating since 1999

Gasification and Pyrolysis

Gasification

Utilizes Thermal Energy developed by Plasma Torches at Temperatures ≤5,500 Degrees Celsius. All Organic Material is Gasified to form a Synthetic Gas (“Syngas”).

Multiple Feedstock

Advanced Thermal Gasification System

All Inorganic Materials is Vitrified into Inert “High Grade Aggregate Slag”

Calorific Energy and Sensible Heat from the Syngas is Recovered and transformed into Electrical Energy

Advanced Thermal Gasification System

Flexibility of Gasification

Landfill closing and Energy generation

Landfill closing and Energy generation

The main component of landfill gas are methane and carbon dioxide. Both components contribute significantly to the greenhouse effect and are chiefly responsible for global temperature rise.

Municipal solid waste management and wastewater contribute about 3% to current global greenhouse gas emissions, about half of which is methane from landfills. One forecast suggests that without mitigation, this could double by 2020 and quadruple by 2050. Mitigation needs to be a mix of the ‘technical fix’ approach, such as landfill gas collection and utilization, and upstream measures, particularly reduction, reuse, recycling and composting

1. Vertical gas collection wells2. Horizontal gas collection systems3. Gas collection header lines4. Blower5. Condensate collection system6. Gas treatment system

Gas collection system

Power Generation

Conclusions

Landfill should be used as the final destination of the refuse that cannot be further recycled or recovered in any other way.

Combustion remains predominant thermal technology for MSW conversion with realized improvements in emissions

Gasification and Pyrolysis systems now in commercial scale operation but industry still emerging

Advanced Thermal Gasification System is Clean Development Mechanism under Kyoto Protocol.

Comprehensive environmental or life cycle assessments should be completed.

Private sector companies should be encouraged and supported for investment in these green technology

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