Steps Taken to Improve Environmental Practices at theAppleton Sugar Factory

by Fayona Lewis & Delroy Dunkley

Appleton Estates

ABSTRACT

The impact of factory operations on the environment has been a major concern to theJamaican Sugar Industry and to the Appleton Estate in particular.

As part of its modernization and expansion program, Appleton has taken steps to minimizethe negative impact on the environment in the areas of water, air and noise pollution. It isintended that the estate will become compliant with the established “Environmental Code ofPractice for Jamaica’s Sugarcane Industry” and by extension with the standards of theNational Environmental and Planning Agency.

This paper highlights the steps already taken and the plans to be implemented in thedifferent sections of the Factory operations at Appleton, to achieve the stated objectives.

INTRODUCTION

The negative impact of industrial operations on the environment has been a major concernfor many years. The level of concern has increased over time as damage to the environmenthas become more visible. As time progresses there is increased knowledge relating to thecause and effect of damage to the environment. With the identification of these causescomes the development of solutions or codes of practice needed to minimize or eliminatethese effects.

The cane sugar process involves the discharge of waste material into the surroundingenvironment (air and water), most of which is non-toxic but nevertheless have a negativeimpact on the environment and on human life. In addition there is also noise pollution andhigh temperatures which contribute to global warming.

As with all sugar factories there is the need to improve the efficiency of their operations thusminimizing cost and improving profitability, Appleton is no different. Coupled with this isthe need to preserve the environment by minimizing or eliminating pollution. AppletonSugar factory is located very close to one of Jamaica’s major water sources, the Black River,which makes improving our environmental practices even more critical. The major stepstaken by Appleton Estate to satisfy the environmental standards are presented in this paper.These measures are presented under the headings outlined for the Section 2 of theEnvironmental Code of Practice for the Sugar Cane Industry.

SUGAR CANE TESTING

The use of octapol which is a more environmentally friendly chemical (recommended bySIRI) has been in use since the 2001/2002 crop. In addition the chemical is packaged in jarswhich make handling and disposal of waste easier.

The recycling of sample bags has reduced the bulk of solid waste to be disposed of. Solidwaste, mainly bagasse, is stored in a concrete bin for containment. It is removed daily to thedesignated area on the estate for disposal.

CANE YARD MANAGEMENT

Sugar cane is stored over short periods as proper planning is done to ensure that only theestimated cane to be crushed in one day is prepared and delivered to the factory. Sugarcaneconveyance usually results in spillages en route to the plant. The use of side tipping trailersfor the transportation of chopped stick cane and its direct offloading on to the washing planthas significantly reduced spillage.

Dialogue with haulage contractors to prevent overloading of trucks/carts has also helped inthis area. It was pointed out that spillage of raw material on the roads represents loss ofrevenue to both farmers and contractors. Spilt canes are gathered and reused immediatelythus preventing it from becoming a part of the solid waste stream.

In the event that the storage area becomes empty, all debris and dirt is removed from thearea and disposed of in the designated area on the estate.

Off loading chopped stick cane on to the washing plant

Cane Preparation

Washing

The washing plant at the Appleton factory is set at a 45-degree angle. The angle of the plantallows for the use of minimum volume of water to obtain optimum results in terms ofremoval of debris from the cane.

Attempt has been made to avoid the washing of canes and some success has been gained inthis area. Problems were however experienced during periods of high rainfall when washingbecomes necessary.

The discharge of wash water with high sediment level into the nearby river was a majorconcern as there were constant complaints from the fisheries and other users locateddownstream. Out of this concern came the drain separation (Appendix I) and constructionof settling ponds (Appendix III) for cane wash and other high sediment level waste waterAll the factory drains were also modified to allow waste water from other sections of thefactory to be transferred to these ponds.

The settling ponds were constructed in 2005 for use at the start of the 2005/06 crop. Thearrangement consists of a series of five ponds which serves as a holding area and allowssufficient time for sedimentation to occur prior to its discharge into the water course. Thewater enters the first pond and flows through the others before exiting as shown in thefigure below. Although designed for natural aeration we were plagued with foul odor fromthe ponds, thus aerators were fitted to minimize the activity of anaerobic bacteria therebydecreasing air pollution.

Washing Plant

White lime was also used to counter bacteria and odor. The idea to pass the cane wash waterover partially burnt bagasse from the boiler scrubber to decolorize and deodorize metlimited success.

Shredding

Cane preparation takes place in an enclosed area which prevents the discharge of cane fibreparticles into the air. This area is sanitized frequently to prevent the build up of bacteria(particularly dextran). Also any fibre which may have escaped from the shredding area iscleaned up and returned to the carrier system or returned to the fields.

MILLING

During the milling operations, spillage of both cane juice and lubricants used in theoperation of the mills sometimes occur. The effluent from washing of floors which containsoils and grease along with the spilled material passes through an oil trap before being sent tothe settling ponds.

An outline of the oil trap is shown in Appendix II. The principle is that the oils will floatand get trapped on the columns. The trap has to be cleaned periodically to prevent trappedoils from going over when there is high flow in the drains.

It is standard practice at Appleton to wash the mill train twice per shift using hot water. Thiswashing system was set up in 2005 and consists of high pressure spray nozzles connected toa line taken from the boiler feed line. The mills are also sanitized with chemical to preventbacterial growth.

Aerators in the settling ponds

PROCESS HOUSE OPERATIONS

Filter Mud Disposal

The impurities that are separated from the juice consist mainly of mud and some lubricantbased impurities. About 30-50 kg of filter mud is produced per tonne of cane consisting of70% water and 0.9-5% sugar. A 40 ton capacity mud bin was constructed during theexpansion project to collect filter mud. The bin is structured to allow trucks to be loaded byopening the gate at the base of the bin. This reduces spillage. Concrete barriers are used toenclose the loading area under the bin. This provides a containment area for filter mud incase there is spillage.

Removal of filter mud is done continuously thereby preventing piling; in addition the area infront of the bin is sloped away from drains to prevent mud from entering the drains. Themud is transported to the fields and applied as a soil conditioner. During rainy periods, thefilter mud is stored in a holding area until a drier period.

Liquidation of Clarifier

The temperature and content of the mud from the clarifier was considered during themodification of our factory drains. Waste liquidating material is sent via the transfer pumpsto the settling ponds where it is cooled and settled before discharge with the rest of thestreams.

Lime Receipt and Storage

Appleton estate is presently relocating the lime receipt and storage area from the front of thefactory in an effort to reduce dust nuisance. The lime storage area has been relocated insidethe factory where spillage, if any, will end up in the settling ponds. The area provides properstorage facilities for unused material while catering to the safety of personnel. The area willnot be bunded but any spillage will end up in the cane-wash ponds. From this locationaddition of lime to the settling pond will be easily done.

Entrainment from Condensers

Monitoring of pans is a priority especially for Process House personnel. This to avoid"boiling over" of the vessels. One area of concern was the problem of the occasional “carryover” when starting up the “C” continuous vacuum pan. To avoid this ‘C’ CVP was fittedwith an entrainment dome at the start of the 2006/07. Anti foam is also used in the vesselsto reduce carryover.

Evaporator Cleaning

Disposal of Spent Caustic

As per the code (section 2-6) after the evaporators are boiled with caustic soda solution ofabout 65 brix, the spent caustic is returned to the holding tank and new caustic added untilthe desired concentration is achieved. This process is done prior to the scheduled cleaningday. The slurry that forms at the bottom of the tank is diluted before it is disposed of. Thecaustic soda storage area is bunded.

Spill ControlAll crystallizers are fitted with level controllers that can detect above normal levels in thecrystallizers. The levels of these tanks can be monitored from the computer system by aControl Room Operator. The computer system is equipped with an alarm which indicatesto operators when these levels have been reached. In addition to this an attendant isassigned to periodically monitor the levels in the event that the level controllers malfunction.

CentrifugalsCentrifugal baskets are maintained in order to eliminate the incidence of spillage. Theinstallation of a continuous high grade centrifugal has reduced the level of contact with the

product by the operators. Its enclosed design significantly reduces spillages. The sugar fromthe centrifugal passes to a dryer via screw conveyors which are enclosed to avoid spillage andcontamination. The dryer is equipped with a scrubber which traps all sugar dust which isthen sent back to process. En route to storage, sugar travels on a specially designed rubberbelt which is enclosed thus preventing spillage. Sugar is stored in a leak proof metal bin.

The facility is available however for spilt material to renter the system for reboiling. All thepersons who handle the product are required to have a food handler’s permit which isrenewed annually usually just before the start of the crop.

Sugar Storage Silo

BOILER OPERATIONS

Boilers have always been a major source of pollution to air, land and sometimes water. Asfor Appleton, boilers have been polluting the air to a great extent and the land to a lesserone. The air is being polluted by the fly ash from the flue gas emission and the lands by theunburnt bagasse and cinder that are removed from the furnace during cleaning.

During crop steam is supplied by a 220,000lbs/hr bagasse fired boiler which has resulted insignificant reduction in the use of fossil fuel. The production of sulphur oxides and nitrousoxides is significantly reduced. The boiler is equipped with hoppers at various points toremove the coarse ash and grit. The gas then passes through a cyclonic wet gas scrubber,which enables the stack emissions to be free of particles. The collected ash is sluiced into a concrete trough, channeled to a sump and pumped to aseries of settling ponds where the clean overflow discharges into the river. The ash ponds arecleaned periodically and at the end of crop and the ash used as soil conditioner. It should benoted that the improved use of the flue gas heat and the presence of the wet scrubberreduces the temperature of the gas emitted to the atmosphere (Approx. 160 F).

The design of the Bagasse Fired Boiler enables bagasse of high ash content (dirty) to beburnt quite efficiently. As a result, the washing of cane can be significantly reduced oreliminated, thus easing the problem of disposal of cane-wash water and its consequentimpact on the environment.

An oil trap was also constructed for the oil fired boilers to capture any spillage of fuel. Toreduce noise a new exhaust steam relief valve equipped with silencer is being installed forthe start of the next crop. This will replace the present ones which are very noisy.

Boiler Stack Emission

Storage of surplus bagasse was also a problem due to the large area required and the rapiddegradation when left in the open. There was also the problem of bagasse being carried bywind causing a dust nuisance. To eliminate this problem a 1000 tonne bagasse bin wasconstructed. The bin is totally enclosed and the bagasse travels via covered conveyor belts toand from the bin.

Bagacillo for use in filter mud is dispensed to screw conveyors via chutes to reduce dustnuisance caused by these small particles becoming air borne.

Transition points between conveyors remain sources of dust nuisance to be overcome.

Bagacillo Chutes

Bagasse Bin

Power House

The power house is usually an area with very high noise levels. This has proven to benuisance to operators even with the use of ear protectors. A control room for the powerhouse has been constructed with sound proof material which has significantly reduced thenoise level in the switchboard area. The diesel exhaust piping has been thermally insulatedwhich, in addition to heat reduction has reduced the noise level to approximately 100decibels. Plans are in place to have the silencers for mufflers relocated closer to the unit toreduce further noise level to the recommended 65 decibels.

Waste oil from the diesel generators is recollected in metal drums and used by haulagecontractors in their hydraulic systems. Plans are being made to have this oil recycled to theBunker C oil tank.

PROCESS EFFLUENT TREATMENT AND DISPOSAL

In April 2006 water samples were taken from the river, at the inlet of the first pond and theoutlet of the last pond. Analyses were done on each sample the results of which werecompared with the results of samples taken within the same month in 2005 at the samesample points.

The results show that the ponds have improved the treatment process of waste water andmost of the parameters are in compliance with NEPA Standards. It was seen that ChemicalOxygen Demand (COD) between intake to the first pond and outlet from the second pondwas reduced by 77.29%. There was a decrease in Total Suspended Solids (TSS) of 66.18%.Other results were as follows:

Nitrate reduced by 86%

Phosphate reduced by 99.6%

Total Dissolved Solids reduced by 66.18%.

All these are below the NEPA standards in addition to sulfates, oil and grease.

GENERAL

Old metal is sold to scrap metal dealers thus preventing the pile up of metal at the factory.

All personnel are provided with protective and safety equipment. Safety audits are conductedperiodically to ensure compliance to the required standards.

CONCLUSION

With the modernization of the plant, the Appleton factory has taken the necessary steps tooperate closely to the outlined environmental code of practice. This mode of operation notonly saves the environment but also saves the company.

This drive is however an ongoing one. This is the first year of operation for the settlingponds and as such improvement work is continuing. The following improvement methodsare being looked at:

The use of elbows on the connecting pipes to reduce the flow rate of the water betweenponds. The elbows will be turned down on the inlet side and turned upwards on thedischarge side. This would make the ponds more efficient in trapping solids.

Chlorination of the waste water before the final pond and allowing sufficient contacttime before discharge into the river.

The construction of two additional ponds and the use of water hyacinth to reduce TSSand in turn reduce COD.

ACKNOWLEDGMENTS

The writers wish to express gratitude to the following persons who made this presentationpossible:

The Management of J. Wray & Nephew, Appleton Estate for granting permission forthis presentation to be made.

Mr. Everett Williams for his assistance with data Messrs. Richard Bryan and Delroy Foster for their advice and assistance in editing.

Thanks to all other individuals who have assisted indirectly in the completion of thispresentation.

APPENDIX I

Outline of Drain Separation

#2 boiler

mill

s

Washwaterpumps

Clarifier

Sugar lab

S/lab sewer tank

Vertical crystallizer

Continuous V/pans

sealing well

Evap condenser

sealing well

OC filter sealing well

Lime tank

Mixed juice tank

Mud

tank

Evap washout

Fugalstation

CANE YARD

ABC

DE

F

G

H

blin

d

blind

blind

blind

I

J

Condenser discharge drain

Bat

chpa

nsse

alin

gw

ell

Oil trap

To M.J. tank

APPENDIX II

Outline of Oil Trap

APPENDIX III

Sections of the Settling Ponds