An attempt has been made to distinguish the advantages and disadvantages of different treatment methods of bamboo and the same is presented.
Bamboo plays a dominant role as woody raw material for a variety of products. However, bamboo is non-durable as it is liable to attack by fungi and insects. So, several methods are employed to enhance its durability.
Treatment of Green (Fresh) Bamboo:
(i) Steeping
(ii) Sap-displacement
(iii) Diffusion process
(iv) Boucherie process
Advantages:
(1) Bamboos can be satisfactorily treated by this method without any equipment and technical skill
(2) Round, half, quarter and 1/8 split Green bamboos can be treated
Disadvantages:
(1) Ineffective against termites and fungi
(2) Traditional methods are of limited value
(3) Not favored because of environmental problem
Treatment of Dry Bamboo:
(I) Soaking:
Advantages:
1. Bamboos can be satisfactorily treated by this method without any equipment and technical skill.
Disadvantages:
(1) Soaking method requires little equipment and technical knowledge, provided the schedule of treatment such as type of preservation, its concentration and the period of dipping is worked out.
(2) Danger of pollution due to spillage.
(II) Hot – Cold Process:
Advantages:
(1) Both round and split bamboo can be treated.
Disadvantages:
(1) It is not widely in use due to the economic aspects.
(III) Pressure Treatment:
Advantages:
(1) Treatment with water- borne preservatives likes CCA can be done effectively.
Disadvantages:
(1) It is theoretically possible to use pressure treatment but general applicability in a number of countries has not yet been developed.
(2) The problem of collapse of round bamboo under pressure treatment.
a. Traditional Methods:
1. Non-Chemical Methods:
(i) Felling of bamboo during low-sugar content season
(ii) Felling of bamboo at maturity when sugar content is low
(iii) Post-harvesting transpiration of bamboo culm
(iv) Water soaking of bamboo
(v) Lime washing and other coatings
Advantages:
Without special equipment and technical know – how
Disadvantages:
(1) Not applicable to all ages of Bamboos.
(2) Treatment schedule can’t be done
(3) Treatment of Green Bamboo can’t be applicable
2. Backing Over Open-Fire:
Advantages:
Very useful for simultaneous straightening of bamboo in round form.
Disadvantages:
Excessive heating/drying can cause severe collapse.
b. Chemical Preservation Methods:
Advantages:
(1) Ensures longer life for Bamboos
(2) Can be applicable for both green and dry Bamboos
Disadvantages:
Needs skill and a definite treatment schedule
Environmental Aspects of Treating Bamboos with Preservatives:
Methods of traditional (non-chemical) techniques are absolutely safe and pose no threat of environmental pollution. At the same time, these methods have limited tope in extending bamboo’s service life.
Chemical preservation strategies employ chemicals toxic to fungi and insects and are invariably toxic to mammals. Slight carelessness in the use of such chemicals can endanger the safety of workers handling the chemicals on freshly treated material.
Although, the preservatives recommended for bamboo have long safety records, here, chemicals are under constant security by various pollution control agencies. The very name of arsenic in preservative formulation raises an alarm in the minds of environmentalists.
Formulations containing arsenic and chromium have been rigorously tested for leaching in laboratory and under service conditions and meet current safety standards. CCA treated materials are considered absolutely safe and have been recommended for the treatment of playground equipment.
Such formulations make complexes with wood substance and are rendered immobile to cause any toxicity concern. Pollution hazards do exist at formulation as well as impregnation sites.
It is suggested that ready-to-use premixed formulations be used to eliminate such hazards and necessary safety precautions as suggested by the manufactures be followed. Treatment effluents, if generated on a large quantity should be adequately treated before disposal.
Pentachlorophenol is another chemical being viewed cautiously. The present technology of manufacture of this compound claims that no dioxins are produced in the process. Nevertheless, disposal of all treated wood products and residues have to meet the toxicity characteristic leaching produced limits (TCLP), proposed by the Environmental Protection Agency (EPA) of the USA.
Boric – acid- borax, Cu/Zn, naphthenates / abietates are among the safest wood preservatives being promoted the world over. Many new chemicals considered to be environmentally safe such as Tebyconazole, IOBC (3-iodo2-propanyl butyl carbonate), chloro- thalonil, isothiozolones and synthetic pyrethroides are under various tag of adoption as wood preservatives. A part from being expensive such chemical need to be tested for their efficacy on bamboos.
Disposal of preservative treated bamboo after prolonged service causes problems in several countries. In some, it is not considered a hazardous waste, but in others it has to be brought to special dumping places.
Proper safety garments such as gloves, aprons, and eye protective glasses should be used while handling preservative solutions of freshly treated materials. Any spillage of chemicals should be immediately attended to by soaking in wood dust and disposed appropriately. Freshly treated materials should be store under over during drying to avoid rain leaching of chemicals.