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In this assignment we would like to discuss about the use of a new technology called the sawdust bio-mixture in the waste technology and also in the environmental management. The industrial wastewater of potato-chips factory is characterized by its high biological oxygen demand (BOD) and chemical oxygen demand (COD), in addition to a medium content of oil & grease, total dissolved salts (TDS) and total suspended solids (TSS). For the treatment of wastewater a new method has been employed using bio-mixture of selected strains of Aspergillus terreus or Rhizopus sexualis in addition to the natural flora of sawdust (SD-BIOMIX) in the form of mobile micro-carrier in activated sludge system. Composted sawdust of various kinds were used as a microbial carrier, support and source of nutrients and enzymes to enhance the wastewater treatment process, in order to improve the quality of treated wastewater and resulting sludge. The sludge, according the chemical analysis, can be safely used in agriculture as an organic fertilizer and soil conditioner. Some other kinds of sludge can be used for testing as biosorbents and can exhibit high ability to remove chromium, nickel and zinc from the heavy industrial wastewater. From the Data indicated in the recent experiments shows the possibility of magnifying the introduced (SD-BIOMIX) as a new technique for the treatment of wastewater and as new trend for wastes management and pollution prevention and could be applied in Australia as one of advanced biotechnology to solve many of environmental problems in Australia.
Keywords: A. terreus, environmental management, R. sexualis , sawdust, waste-waste treatment
Environmental management, wastes recycling, treatment and disposal, pollution control and prevention and wastewater reuse became the most important issues and are in the top of the global agenda [1, 2, 3]. Waste water usually can be processed for disposal or recycling by one or more steps. The first step, usually, the preliminary and primary treatment, which is physico - chemical treatment. Because of the objection properties of the effluent, the secondary treatment, which is biological treatment, is employed. The operation involves the biological degradation of organics; both dissolved or suspended materials by microorganisms under controlled conditions . Biological treatment can be accomplished in a number of ways, but the basic characteristic of the system is the use of mixed microbial culture; bacteria, fungi and / or algae, for the conversion of pollutants. In most of the cases, organic materials are converted to oxidized products, mostly carbon dioxide and new microbial cells (the sludge). The organic materials serve as an energy and carbon sources for cell growth [5, 6, 7]. Biological treatment can be divided into two configurations in common use: film flow (fixed - film flow system) and suspended or fluidized culture. Suspended-culture processes are in use which includes activated sludge, aerated lagoons, oxidation ponds and anaerobic treatment process [5, 8, 9, 10]. Trickling filter is one of the most common used example of film - flow - type process. Wastewater is sprayed over a bed of support media (gravel, rock or plastic balls) covered with a biological film [4,5]. Other configurations of film - flow reactors are the rotating biological contactor. This system utilizes lightweight materials such as Styrofoam to support microbial film and the system operates by moving the microbial film though the wastewater. Industries that have found the trickling filter and rotating biological contactor processes especially suitable are the food products industries [11, 12]. In recent times, Industrial wastewater of potato - chips factory has been successfully treated by new method , which could be classified as one of suspended culture processes. Starch - wastewater was treated by modified technique of suspended growth systems [14, 15]. Generally potato - chips wastewater is usually characterized by high content of organic materials which are the direct reason for the high biological and chemical oxygen demands (BOD & COD) of the factory wastewater . On the other hand, thousands tons of organic and agriculture solid waste mainly plant waste materials (PWM) e.g. rice straw, bagasse and sawdust are accumulated in the environment [1, 16]. Most of these materials (P.W.M) are burnt in the field causing air - pollution and health problems. In this work, one of the solid wastes, sawdust is used as microbial supporting matrix and biomixture in new system of biological treatment (as bioconductor- suspended culture) to treat wastewater from potato - chips producing factory.
The main target of the present work is a trial to apply new technique to improve both the wastewater and sludge quality, as well as the reuse of the resulting sludge in agriculture as fertilizer, soil condition and water holder; and in heavy industry as a metal biosorbent.
Materials & Methods:
Collection and preparation of samples:
To do this work, wastewater of potato-chips factory should be collected, at the end-pipe, in sterile clean glass bottles, then store at 4Â°C. Few bottles of galvanizing wastewater should be collected in clean bottles.
Use of fungi:
Aspergillus terreus and/or Rhizopus sexualis can be used as test organisms for the treatment processes of wastewater and rice-sawdust.
Collection and preparation of Sawdust:
Sawdust should be collected from any of the wood workshop and then be divided into some equal parts. First part should be kept as it is, and it will be used in the waste water treatment. Second part should be mixed with some amount of potato-chips wastewater which was collected in glass-jar. Third and fourth parts were treated as second one. Then third and fourth ones should be cultivated with the fungus. After a week or two the glass-jars will be incubated at 25 Â°C.
The microbial / fungal growth on/in the sawdust can be investigated microscopically. Some Amounts of fresh municipal sludge should be collected; the major parts of the sludge have to be dried in the air for 8 days to constant weight. One gm of non-composted or composted sawdust or sludge is to be suspended in distilled water, filtrated, and filtrate is to be examined for its enzymatic content [16, 17].
Potato-chips wastewater treatment:
The primary treatment of the potato-chips wastewater can be run according to Kerri et. al. (1995) by using 1% of alum and left to settle down for 15 min. then two litres of the wastewater has been transferred to clean glass-jar. The second (biological) treatment; one litre of the primary treated wastewater could be run according to the introduced new technique (SD-BIOMIX). Some bi-products are mixed, separately, with one liter of primary treated wastewater, in 2 liters steering glass-jar under aerobic conditions for 4 or 8 h. at 25 Â°C. The wastewater will be left to settle down for Â½ h, the precipitated sludge amount should be measured, time-to-time., and calculated (v/v) in percentage. The wastewater could be separated from the sludge then, its parameters before and after the treatment, would be determined . The amount of settling sludge will be divided into two parts: The first part was analysed for its parameters . The Standards of Agriculture for the possible use as soil fertilizer and conditioner in agricultural will be recognized. The second part of the sludge can be examined for its use as biosorbent to remove heavy metals from galvanizing wastewater .
Expected outcome of the above methods:
The enzymatic contents of the tested materials after 14 days of incubation or composting using various liquid or solid waste media should be measured. Both the municipal sludge and non-composted sawdust will have low concentration of cellulase(s) with little bit of Î±-amylase(s), in case of non-composted sawdust, also both Î±- amylase(s) and protease(s) will be of low concentration in the culture filtrate. The enzymatic productivity of the two fungi grown in sawdust will be appeared to be higher than it in Czapeck's medium. Results indicated that sawdust gave high yield of enzymes. The composted sawdust, as biomixture of sawdust and fungal growth will be served as an enzymatic store, particularly for cellulase(s) and Î±-amylase(s), microbial carrier and biosorbants. The potato chips wastewater must exhibit high BOD, COD, O&G, TDS and TSS, even after the primary treatment and sedimentations.
Biological treatment of the primary treated wastewater by microorganisms or microbial containing materials (bio-mixture) will be the favourable solution. All the materials, except the non-composted sawdust must exhibit range of success in the bio-treatment process of wastewater, particularly; the fungal and microbial composted sawdust (bio-mixture) after retention time of few hours. The use of non-composted sawdust will have drastic effects on the wastewater quality and may lead to the increase of BOD and COD. The parameters of the wastewater treatment by bio-mixtures can be improved for BOD, COD, O&G respectively. The use of municipal sludge or pure fungal growth (pellets) or commercial bio-products (C157 and EM) may be less efficienct in the process of wastewater treatment. The remarkable results were obtained for the TDS ratio which could be reduced during the biological treatment processes by pure fungal pellets or fungal -sawdust compost (bio-mixture) by 67 - 75%, particularly after 8 h of incubation (retention time). These results may indicate the ability of fungal growth or bio-mixture to remove or uptake the salts from wastewater. Furthermore, the settling - time for separation of sludge from wastewater will be reduced to 10 min, in case of the use of bio-mixture of composted sawdust, where, in case of municipal sludge, for example, the separation (settling) time is 20 min. However, the microscopic investigation of sawdust, before and after the inoculation by tested fungi and during the composting processes for 14 days, indicate that, the sawdust has rough surface which is suitable for microbial spores / cells attack and growth on it. Further, the sawdust could be a good supporting matrix for the microbial - film or / and growth.
The different kinds of resulting sludge of wastewater treatment processes which is composed plant materials and microbial biomass (biomixture) are rich with organic contents and microbial biomass which could be considered as humus.
For these reasons, the sludge can be used in many industrial and agricultural applications. In agriculture, the resulting sludge or bio-mixture of the bio-treatment process of potato - chips wastewater exhibited reasonable characters of water holding capacity, organic and minerals contents. These characters are supporting the possible use of these kinds of sludge in agriculture or soil reclamation.
Second is, in metal - industry, the resulting sludge or biomass, with the exception of municipal sludge and non- composted sawdust, exhibited high ability to remove or sorbs heavy metals from industrial wastewater. The bio-mixtures could be used successfully as biosorbents to remove chromium, nickel and zinc from galvanizing wastewater by approximately 95.0 - 99.3 %, 94.7 - 98.0 % and 90.6 - 97.7% respectively, while activated carbon sorption efficiency ranged between 79.0- 81.5%.
Wastewater and solid wastes may the most pollution threatens to the global environment . Sawdust is one of solid wastes of many activities with no real or limited use [1, 6]. The new technique of wastewater treatment is depending on the use of the sawdust with microbial growth or bio-film on / in it as a mobile system which could be considered as fixed - film flow and suspended or fluidized culture [4, 5, 9, 10, 21], and may be called "SD-BIOMIX". The biomixture (SDBIOMIX), has the benefit of the suspended culture processes e.g. activated sludge system and the advantages of the film - flow reactors e.g. trickling filter and rotating biological contactor (RBC) as detailed described in [6, 11]. The experimental results also states that, the sawdust saturated with Potato-chips wastewater is a very good medium for the microbial growth and activities, where microorganisms particularly fungi can produce good amounts of biomass and enzymes.
The results in this work may enhance and support the theory of the use of sawdust in wastewater treatment process as cheap, slow biodegradable and more efficient material than the activated carbon. Furthermore as mentioned before, it's good surface for microbial growth, easy to separate from wastewater and reduces the sludge volume. Although, the total dissolved salts (TDS), may be reduced by 67.5 - 74.6%, thus indicated the desalination ability of tested fungi or bio - mixture. The desalination phenomenon was recorded in some selected strains of fungi .
In conclusion, the application of the mobile biomixture (SD-BIOMIX) in many of industrial wastewater treatment processes may be considered as a new efficient and non-expensive biotechnological solution for many of environmental problems of solid and/ or liquid industrial wastes. Further the work is establish and confirmed the waste-waste treatment technology and a step in sustainable development programs.