Reuse Of Waste Water Commerce Essay

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The beverage and brewery industries are the major consumers of water. They use large amount of water daily but only a part of water is turned into end products. Most of the water is used for cleaning the returned bottles. Hot water with a temperature of 70 to 80oC is used to rinse the returned bottles after soaked inside the sodium hydroxide solution. Due to the factory want to reduce the basics cost, recycle and reuse water are the best way to be. Membrane filtration is suitable for processing this type of waste water. It can be divided into four different parts. Each part has its unique size for retaining the different particles. This four parts are reverse osmosis (RO), ultrafiltration (UF), microfiltration and electrodialysis. First three parts can retain the size of particles from (I) the ionic range is between 3 to 1000 Šin RO; (II) the molecular range is between 0.002 to 0.05 µm in UF; (III) the macro molecular range is between 0.05 to 10 µm in microfiltration. Besides that, the particles will not clog on the pore of membrane due to repulsion of ions from the membranes. According to Membrane filtration for reuse of wastewater from beverage industry, the waste water is alkali water and the pH is 8.5 due to present of sodium hydroxide. The organic matters are measured in chemical oxygen demand (COD).

Parameter

City Water Supply

Raw Wastewater

Ultra-Filtration system

Reverse Osmosis system

pH

7.5

8.5

7.5

7.4

COD (mg/L)

-

680.0

30.0

4.0

Turbidity

0.8

11.0

<0.1

<0.1

Colour

(Hazen Unit)

<5.0

90.0

<5.0

<5.0

Total dissolved solids (mg/L)

50.0

3370.0

170.0

23.0

Conductivity (µs/cm)

70.0

3360.0

168.0

20.0

Temperature(oC)

26

65-70

50-51

35-40

Total coliform group

ND

ND

ND

ND

E.Coli

ND

ND

ND

ND

*ND = No Detectable

Table 1 - Characteristics of raw wastewater and effluent

(Source: Membrane filtration for reuse of wastewater from beverage industry)

The contents of wastewater have been shown in Table 1. In order to treat wastewater for reusing, the brewery can build either ultrafiltration system or reverse osmosis system.

Ultrafiltration System

If we separate out the ultrafiltration process, it consists of storage tank, ultrafiltration unit and cartridge filter which is used to remove large particles. 4.5 to 6.5 bars of pressure is needed for membrane system and the permeate flux is operating at 178 L/m2h. The ultrafiltration unit is drawn in Figure 1. Area of 2.25 m2 is used for the membrane.

Concentrate

Pump

Raw Water

Pump

Permeate

Ultrafiltration Unit OR Reverse Osmosis Cartridge

Filter

Holding Tank

Figure 1: Ultrafiltration System

(Source: Membrane filtration for reuse of wastewater from beverage industry)

Due to slower flux rate, the temperature of the contents increases from 41 to 51oC. When the time reaches 49th, 139th and 189th minutes, the factory will add second, third and fourth batches of raw water respectively. To achieve maximum performance, the pressure is fixed on 6.1 bars whereas the concentrate flow rate is 8.1m3/h to 8.2m3/h. After finished the whole process, the ultrafiltration system can remove up to 95% impurities from the waste water. Because of this, the standard of treated effluent is accepted and can be used for cleaning the returned bottles. The temperature for the treated effluent is at 50 to 51oC which is much higher than the city water supply. So, the brewery can reduce the energy required for heating the water to clean the bottles.

Reverse Osmosis System (RO)

Storage tank, 30 microns cartridge filter and a reverse osmosis unit are installed under reverse osmosis plant. RO plant needs 35 to 37 bars of pressure to operate and the permeate flux rate is at 68 L/m2h. Based on Membrane filtration for reuse of wastewater from beverage industry, the membrane is washed with 0.5% Ethylenediaminetetraacetic acid (EDTA) solution, 0.3% Ultrasil 11 solution, 0.3% nitric acid solution and again 0.5% EDTA solution. If the breweries shorts of 0.3% nitric acid, they can use 0.2% sodium hydroxide solution as an alternative way to wash the membrane. Over the 160 hours of operation, the conductivity of permeate is continuing to increase from 30µs/cm to 57µs/cm. In fact, the RO can remove more than 99% of the impurities from the wastewater. This kind of treated effluent can be used as potable water.

By comparison, the ultrafiltration system can produce higher flux at a steady rate and low pressure whereas the reverse osmosis system needs frequently washing the membrane and high operating pressure. From here, we can see that the quality of treated effluent from reverse osmosis is better than ultrafiltration. In other words, the quality of treated effluent of ultrafiltration system is almost same like the city water supply. For maintenance of the membrane filtration, the brewery needs to add a coagulant to aggregate the small colloids and macromolecules together in order to avoid the blockage to passage of water.

Biological Treatment for brewery

Biological treatment for the effluent of brewery also is a good method and no side effects for the environment. Biological treatment can be divided into two, one is aerobic another one is anaerobic. To undergo biological treatment, the effluent must reach the ratio of COD/BOD at 1.8 - 1.9. For aerobic treatment, the effluent should has high organic load and other systems unable to treat high BOD or COD. When the ratio of BOD: N: P reaches 100:2.4:0.3, the effluent should undergo anaerobic treatment first so that the pollution of distillery effluent can be minimized. Table 2 is provided with the information of characteristics of untreated and anaerobically treated distillery effluent.

Parameters

Values of Distillery Effluent

Values of anaerobically treated effluent

pH

3.0 - 4.5

7.5 - 8

BOD (mg/L)

50,000 - 60,000

8000 - 10,000

COD (mg/L)

110,000 - 190,000

45,000 - 52,000

Total Solid (TS) (mg/L)

110,000 - 190,000

70,000 - 75,000

Total Volatile Solid (TVS) (mg/L)

80,000 - 120,000

68,000 - 70,000

Total Suspended Solid (TSS) (mg/L)

13,000 - 15,000

38,000 - 42,000

Total Dissolved Solids (TDS) (mg/L)

90,000 - 150,000

30,000 - 32,000

Chlorides (mg/L)

8000 - 8500

7000 - 9000

Phenols (mg/L)

8000 - 10,000

7000 - 8000

Sulphate (mg/L)

7500 - 9000

3000 - 5000

Phosphate (mg/L)

2500 - 2700

1500 - 1700

Total nitrogen (mg/L)

5000 - 7000

4000 - 4200

Table 2: Characteristics of untreated and anaerobically treated distillery effluent

(Source: Journal of Hazardous Materials)

Single-phasic and biphasic anaerobic system (Anaerobic)

Anaerobic systems can be carried out in single-phase or two-phase systems. Single-phase means the process only involve one reactor which is occupied by the microorganisms to digest the organic matter. For the two-phase systems, it uses the acidogenic and methanogenic organisms in two separate reactors. The biphasic system is able to optimize the fermentation steps in each fermenter. The efficiency and kinetics of biphasic system are higher than single stage which all organisms and fermentation are conducted under the same environmental conditions. The end products for the primary phase of fermentation are ethanol, carbon dioxide, hydrogen, C3, higher volatile fatty acids, formate, acetate and lactate. Because of this, this phase can be classified as acid fermentation. The second phase system is acetotrophic methane fermentation and produces methane and carbon dioxide. Biomethanation is a good way to treat high strength waste water and using biphasic system. According to Journal of Hazardous Materials, the advantages of Biomethanation are maintaining the optimal conditions for buffering of imbalances between organic acid production and consumption, higher methane concentration in the biogas produced. For anaerobic system, the normal chemical equation is:

COD CH4 (g) + CO2 (g) + Anaerobic Biomass

Fungal System (Aerobic)

Fungi are a eukaryotic organism and able to produce many different proteins, organic acids and other metabolites in order to suit in different living environment. A fungi group member, Aspergillus species is able to decolorize the distillery effluent on an average of 69 - 75% and reduce the COD level up to 90%. Pentcillium species also has a function to reduce the colour intensity of distillery effluent, bring down the COD level and cut down 70% of phenol. The pigments will accumulate in the cytoplasm and then slowly decolorized by intracellular enzymes. Bioremediation is also used in treatment of effluent and involving aerobic system. It uses white rot fungi as a disintegrator in the whole process. White rot fungi will produce extracellular oxidases such as laccases, lignin peroxidase and manganese peroxides. These substances are used to degrade the lignin in their lignocellulosic substrate. The white rot fungi also have a ligninolytic system which is straight away to degrade the xenobiotic compounds and dyes. For aerobic system, the normal chemical equation is:

COD + O2 (g) CO2 (g) + H2O (l) + Aerobic Biomass

Table 3 is to show the comparison of two systems (Anaerobic and Aerobic).

Anaerobic System

Aerobic System

Energy Consumption

Low

High

Energy Production

Yes

No

Biosolids Production

Low

High

COD Removal

70 - 85%

90 - 98%

Nutrients (N/P) Removal

Low

High

Space Requirements

Low

High

Discontinuous Operation

Easy

Difficult

Table 3: Comparison of anaerobic and aerobic systems

(Source: RECENT DEVELOPMENTS IN BIOLOGICAL TREATMENT OF BREWERY EFFLUENT)

Disposal of Brewery Effluents by Land Application

Land application is only applied on high strength brewery effluents. Based on Brewery By-Products and Effluents, the land system can tolerate an average of fluid loading of 0.12 inch/day, a suspended solids loading of 43 lb/acre/day and nitrogen loading of 595 lb N/acre/year. After separation, the high strength effluents are collected in a stainless steel tank which located on the ground. This tank can take capacity up to 3.6 days. During this time, the tank needs to minimize the odour problems and pH is adjusted so that these effluents can be accepted by particular soil. After that, the effluents must pass through a screen to prevent any solid to clogging up the irrigation system. The workers need to do a lot of preparation on the soil so that it can maintain 3 feets of water level over the entire area. This soil also can be planted with turf grass and able to be harvested in every 4 to 6 months a year.

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