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Five years of water recycling at the Panipat Refinery, India J. Lahnsteiner*, P. Andrade** and R. D. Mittal*** *VA TECH WABAG GmbH, Dresdner Strasse 87-91, 1200 Vienna, Austria (E-mail: josef.lahnsteiner@wabag.com) * *VA TECH WABAG Ltd, Bhakti Plaza, 2nd Floor, Aundh - 411007, Pune, India (E-mail: patrick.pune@wabag.in) ** * VA TECH WABAG Ltd, 11, Murray´s Gate Road, Alwarpet, Chennai 600 018, India (E-mail: r_mittal@wabag.in) Abstract The Indian Oil Corporation Ltd. Panipat had to build two water reclamation plants as a response to the demands of the environmental authorities. The plants, which treat secondary refinery and various refinery/petrochemical process effluents, were commissioned in 2006 and 2010 respectively. Advanced multi-barrier systems (including ultrafiltration and reverse osmosis) have been employed in order to meet the stringent quality requirements for the recycling of boiler make-up water. Excellent results with regard to the removal of the major parameters such as total dissolved solids (TDS) and silica have been accomplished, e.g. silica is mainly removed by RO (from 11.6 mg/L in the UF outlet to 0.09 mg/L in the RO permeate (99.2 % removal)) and is then reduced further to 0.007 mg/L (7 µg/L; total removal 99.94 %) in the mixed bed ion exchanger (20 µg/L is the specified limit for boiler make-up water in various power plant guidelines). Both UF process units have shown relatively good performance. The older UF has been in operation for approximately five and a half years (by May 2012). Most of the membranes (ca. 80%) have been exchanged gradually during the last one and a half years. The number of fibre breakages has been relatively low.

Keywords

Water recycling, refinery effluents, ultrafiltration, reverse osmosis, boiler make-up water

INTRODUCTION On January 31, 2012 India´s Ministry of Water Resources announced a new draft water policy (GWI, 2012). This document includes a set of provisions (national Water Framework Law, etc.), which if finally implemented, will cause a “quantum leap” in Indian water management. Subsidies and incentives are foreseen for the industrial sector in order to encourage water recycling and reuse. This will further promote industrial water reclamation, which in several special cases was already implemented in the middle of the last decade. In this context, industrial water recycling and reuse in Chennai the capital city of the state of Tamil Nadu is worthy of mention as a prime example. In this water-stressed city, reclaimed water (from secondary municipal effluent and internal effluents) is reused or recycled by industrial companies such as Chennai Petroleum Corporation Ltd (CPCL), Madras Fertilizer Ltd and Manali Petro Chemicals (Lahnsteiner 2010). The reason for reuse and recycling is the chronic water shortage in the Chennai metropolitan area, i.e. all available sources including seawater desalination have to be employed. Furthermore, it must be mentioned that whenever there is a drought, the authorities first cut off industry from the public water supply. Another example is reclamation and recycling at the Indian Oil Corporation Ltd. (IOCL) refinery in the seaport town of Paradip, which is located on the Bay of Bengal in the state of Orissa. The major reason for recycling in this case is that reclaimed water is cheaper than seawater desalination. The reclamation plant employs an advanced multi-barrier system (including UF and RO) with a design capacity of 26,500 m3/day (reclaimed water, i.e. RO permeate) and will become operative in the second half of 2012. Apart from the reclamation plant, the overall wastewater management system includes the pre-treatment of different refinery effluents (e.g. wet air oxidation of spent caustic

soda), secondary biological treatment and the treatment of RO brine (removal of recalcitrant COD) by PAC adsorption.

In this paper, recycling plants at the IOCL Panipat refinery and petrochemical complex are presented and compared. The original Panipat refinery (6 million metric tons per annum [MMTPA]) was commissioned in 1998 and the refinery expansion (doubling of refining capacity) commissioned in 2006. This expansion also included the petrochemical production of paraxylene (PX) and purified terephtalic acid (PTA), which form the basis for producing polyester staple fibres, polyester filament yarns and other resins. The Panipat Refinery Expansion Water Reclamation Plant (PRE-WRP), which treats both secondary refinery effluents and various refinery/petrochemical process effluents, was commissioned at the end of 2006. In 2009 the refinery was further expanded to 15 MMTPA. The naphtha cracker and its downstream polymer units (Naphtha Cracker Complex) were commissioned in 2010. The Panipat Naphtha Cracker Water Reclamation Plant (PNC-WRP), which is virtually identical with the PRE-WRP (practically the same process and hydraulic capacity but with a different RO design) and reclaims process water from naphtha cracker secondary effluent, cooling tower blow-downs and demineralisation regenerates, went on-line in June 2010.

IOCL is India’s largest commercial enterprise and was ranked 125th on the Fortune Global 500 list in 2010. It owns and operates ten of India’s 19 refineries with a combined refining capacity of 65.7 million metric tons per annum (MMTPA).

Panipat is located in Haryana State, 90 km northwest of Delhi. Annual precipitation totals approx. 500 mm, but over 70 % of this rainfall occurs during the monsoon months of July to September. Nevertheless, there is practically no water shortage in the Panipat region due to the availability of sufficient surface water (river water). The Panipat Refinery is located in farmland irrigated by the Yamuna canal, which is used mainly for potable water production and agricultural irrigation and thus cannot be employed as a recipient. Therefore, rather than due to a lack of water for industrial use, reclamation plants have been installed to meet stringent governmental regulations (zero liquid discharge in the mid-term) and prevent the pollution of nearby water bodies. Water losses during the refining processes are compensated for by fresh water from the Yamuna canal. The reclamation of secondary municipal effluent was not considered due to the availability of sufficient volumes of fresh water, the distance between the municipal sewage treatment plant and the refinery, and the installation of zero liquid discharge facilities in the mid-term.

METHODOLOGY In both cases, advanced multi-barrier systems have been utilised in order to meet the strict quality requirements for the recycling as boiler make-up water. As mentioned above, both reclamation plants are located at the Panipat Refinery and Petrochemical Complex, VA TECH WABAG India having been commissioned with their construction, operation and surveillance. The following represents a description of the two cases.

The different wastewater streams treated in the reclamation plants (PRE-WRP and PNC-WRP) are shown in Table 1.

Table 1 Panipat Refinery and Naphtha Cracker Plant - Wastewater Streams

Reclamation Plants – Flow Wastewater Streams Unit PRE-WRP PNC-WRP Secondary refinery effluent - ETP I m3/h 400 Secondary refinery effluent - ETP II1)

PX2)/PTA3) effluent including cooling tower blow-down Demineralisation regenerate from Panipat Refinery I Demineralisation regenerate from Panipat Refinery II1) Cooling tower blow-down from in-house power plant I Cooling tower blow-down from in-house power plant II1) Secondary naphtha cracker effluent - ETP Cooling tower 1 blow down – NCU4) Cooling tower 2 blow down - Polymer Cooling tower 3 blow down - CPP5) Blow down from CPP boiler CPU6) wastewater (intermittent)

m3/h m3/h m3/h m3/h m3/h m3/h

m3/h m3/h m3/h m3/h m3/h m3/h

300 272 60 140 18 50

150 308 253 130 15 45

1)Expansion of refinery; 2)PX…Para-Xylene; 3)PTA...Purified Terephtalic Acid; 4) NCU…Naphtha Cracker Unit; 5) CPP…Cogeneration Power Plant; 6) CPU…Condensate Polishing Unit The major design parameters of the blended wastewater flows (inlet to the reclamation plants) are shown in Table 2.

Table 2 Design Parameters of PRE-WRP and PNC-WRP

Water Reclamation Plants Parameter Unit PRE_RP PNC_RP T °C 15-35 25 TDS Silica COD

BOD5

mg/L mg/L mg/L mg/L

1,786 98 150 10

800 100 125 10

Oil mg/L 10 5 Q m3/h 900 871

Basically, the reclamation plants (design capacity = 900 for PRE-WRP and 871 m3/h for PNC-WRP) incorporate high rate clarification, pressure sand filtration, ultrafiltration (UF) and reverse osmosis (RO) phases. The RO permeate is polished by mixed bed ion exchange filters and is then mostly recycled as boiler make-up water for the refinery and naphtha cracker power plants. Figure 1 shows the process flow diagram, which is more or less representative for both reclamation plants. The major difference is in the RO design (three stages in PRE-WRP, two stages in PNC-WRP). Figure 2 shows the PRE-WRP process units high rate clarification (left), as well as sand filtration and mixed bed ion-exchanger (right).

Figure 1Water reclamation and recycling process diagram – PRE-WRP

Figure 2 High rate clarifier (left), sand filtration and mixed bed ion-exchanger (right)

Figure 3 shows a 3D drawing of the PRE-WRP process steps sand filtration, ultrafiltration, reverse osmosis and mixed bed ion exchanger, which are contained in a building (the high rate clarifiers are as can be seen above in the open air).

Figure 3 3D PRE-WRP representation

Membrane process steps in both plants The same UF and RO membranes are employed in both plants. The ultrafiltration process steps consist of pressure-driven, inside-out, hollow fibre systems (X-Flow Xiga; Table 3). Both systems are operated in a dead-end mode. The major task of the UF is to reduce the silt density index (SDI) and remove turbidity, as well as suspended and colloidal matter, in order to minimise fouling of the downstream reverse osmosis process step. The UF membrane fouling caused by the aforementioned impurities is removed by regular backwashing with permeate. The backwash is enhanced once a day in both UF plants using chemicals (chemical enhanced backwash - CEB with caustic NaOCl and HCl). As can be seen in Table 3, both UF systems were designed with a comparable flux (46 L/m2

·h resp. 44 L/m2·h net flux). The resulting membrane areas are 16,416 m2 for the PRE-WRP UF and 17,280 m2 for the PNC-WRP UF. The retentate of the PRE-WRP UF process step is recycled to the equalisation tanks (feed collection tanks) upstream of the pre-treatment stages of the reclamation plant. The retentate of the PNC-WRP UF is reused in the fire fighting water system together with the dual media filter backwash water, the RO II brine and the mixed bed ion-exchanger regenerate.

Table 3 Ultrafiltration design parameters

Membrane parameters PRE-WRP PNC-WRP

Membrane material Hollow fibre polyether-sulfone Hollow fibre polyether-sulfone

Average feed flow [m3/h] 894 870

Design gross flux [L/m2·h] 54 50

Design permeate flow [m³/h] 760 766

Design net flux [L/m2·h] 46 44

Recovery [%] 85 88

Skids 6 (+ 1 standby) 6 (+ 1 standby)

Pressure vessels/skid 18 18

Vessels total 108 108

Elements/vessel 4 4

Elements total 432 432

Membrane area/element [m2] 38 40

Membrane area [m2] 16,416 17,280

In the refinery reclamation plant (PRE-WRP), a two-pass RO system is employed in combination with a brine concentrator. Figure 4 shows the PRE-WRP ultrafiltration and reverse osmosis (first pass) process units. The UF permeate is fed to RO pass I (three internal stages; low fouling composite membranes, Hydranautics LFC 3). The RO I permeate is further desalinated in RO pass II (three internal stages; low fouling composite membranes, Hydranautics LFC 3) and the RO I reject is fed to the brine concentrator (two internal stages; seawater membranes, Hydranautics SWC 3). The brine concentrator permeate is recycled to RO II. The recovery rate accomplished by this process configuration is 90 %. The RO II permeate is degassed and in order to allow the further removal of dissolved solids, polished in mixed bed ion-exchangers containing strong acid cat-ion and strong base an-ion resins mixed in a single vessel. As previously mentioned, the authorities have stipulated that the refinery has to achieve zero liquid discharge. However, it has temporary permission to dispose of the liquid waste (R.O. brine) produced in the reclamation process. Currently 100 % of the brine is used for refinery coke quenching. Other options are to blend the brine with fire-fighting water, or to use it for the irrigation (blended with low TDS water) of the free

land along the refinery perimeter in order to provide green spaces (14 km long “green belt”). Nonetheless, in the mid-term this official request will be met through the installation and operation of evaporation and crystallisation.

Figure 4 The PRE-WRP ultrafiltration and reverse osmosis (first pass) process units

Due to the lower design TDS concentration (800 mg/L) in the PNC-WRP, a single-pass RO system is utilised in combination with a brine concentrator. The UF permeate is fed to the first RO (three internal stages; low fouling composite membranes, Hydranautics LFC 3) and the concentrate from this stage is further treated in the brine concentrator (two internal stages; low fouling composite membranes, Hydranautics LFC 3). The recovery rate accomplished by this RO process configuration is also 90 %. Permeate from RO I (TDS < 15 mg/L) is polished in the mixed bed ion-exchangers and then recycled as boiler make-up. RO II permeate (TDS < 292 mg/L) is blended with treated raw water (Yamuna Canal water; TDS 292 mg/L) and reused mainly as cooling tower make-up. As previously mentioned, the brine from RO II is mixed with dual media filter backwash water, UF backwash water and the regenerate from the mixed bed ion exchangers, and then reused in the fire-fighting water system. The reclamation plant can be operated flexibly, e.g. in case of poor effluent quality the plant can also be operated solely with water from the Yamuna Canal (TDS = 292 mg/L). Furthermore, the amounts of demineralised water (boiler make-up) and RO II permeate (process water) can be adjusted according to the demands on either source.

RESULTS AND DISCUSSION Figure 5 shows a typical diagram of the major parameters (mean values of January 2009) TDS, silica and COD for the Panipat Refinery Expansion Water Reclamation Plant (PRE-WRP). TDS is reduced primarily in the reverse osmosis process step (from 1,148 to 12 mg/L; 99.0 %) and further cut in the mixed bed filter to less than 0.05 mg/L (total removal > 99.996 %). Silica is also mainly removed by RO (from 11.6 mg/L in the UF outlet to 1.4 mg/L in the RO I permeate and to 0.09 mg/L in the RO II permeate; 99.2 % removal in both RO stages) and is then reduced further to 0.007 mg/L (7 µg/L; total removal 99.94 %) in the mixed bed ion exchanger. This represents excellent removal efficiency, as 20 µg/L is the specified limit for boiler make-up water in various power plant guidelines such as the VGB 2006. Colloidal silica is zero, as it is completely removed in the reverse osmosis stages. In the pre-treatment steps (coagulation/sedimentation, sand filtration), COD is reduced from 69 mg/L to 48 mg/L (30.4 %). It is then cut by a further 5 mg/L (from 48 to 43 mg/L) during UF (10.4 %) and from 43 to 0 mg/l in the course of reverse osmosis. These results are also representative for the periods from February to December 2009, 2010, 2011 and January to May 2012 except for TDS, which was recently lower (600 – 900 mg/L) due to changes in the refinery processes. The aforementioned COD reduction in the UF (5 mg/L or 10 %) means that approximately the same amount can be attributed to both the high molecular fraction of the UF inlet (origin: refinery/petrochemical effluent; assumed macro-molecules: polyesters on terephtalic acid

basis, etc.) and hydrophobic compounds, which are adsorbed on the polyether-sulfone membrane. The UF design gross flux of 54 L/m2

·h and a COD reduction of 5 mg/L result in a specific COD removal rate of 270 mg COD/m2·h, which can be regarded as moderate. Organic fouling can be removed relatively easily by CEB with caustic NaOCl (e.g. by saponification of esters), at least during regular operation. Since start-up in December 2006, the PRE-WRP UF has been operated more or less at design flux. SDI outlet values have generally been within a range of 2.1 to 2.8 (e.g. 2.1 in May 2012; inlet SDI is 6.7; the design outlet value is 3.0) and the turbidity values have been less than 0.1 NTU (limit of detection). An integrity test conducted in December 2008 showed that there were only a few fibre breakages - (e.g. in skid G: 36 in 72 membrane elements, i.e. 0.025 ‰ fibre breakages per year; Table 4).

Figure 5 Removal of TDS, COD and silica - PRE-WRP

The ultrafiltration process demonstrated stable filtration performance in the first two years of operation. However, after 26 months of operation, a permeability loss of approximately 25 % was observed. The main reason was that, at the request of the refinery, 50 - 100 m3/h petrochemical effluent had been additionally treated in the reclamation plant. This effluent contained increased COD concentrations in the 200 - 300 mg/l range, which fouled the UF membranes. This fouling has been removed by more frequent CEBs. However, the original permeability values could not be recovered completely (as already mentioned: 25% permeability loss). Basically, relatively high fluctuations in the permeability values have been observed due to unfavourable raw water qualities, which are caused periodically by sub-optimum performance in the upstream biological effluent treatment plants (ETP I and II). The poor performance of the ETPs can be traced to inhibiting or partly toxic substances from the refinery processes and in winter, the low wastewater temperatures (15°C vs. up to 33°C in summer time). It would seem that under these disruptive conditions more macro-molecules leave the ETPs and this subsequently causes fouling on the UF membranes.

In the last quarter of 2010 and first quarter of 2011, after four resp. four and a half years of operation, permeability remained acceptable (70 - 180 L/m2

·h bar), but nevertheless at the client’s request the skid A and B membranes were exchanged for spare membranes (rack A on November 25, 2010; skid B on April 14, 2011). The old membranes (from rack A and B) were integrity tested. Table 4 shows that after four years of operation (3.9 and 4.3 years respectively) there was still a relatively low specific fibre breakage rate (skid A: 119 breakages in 72 membrane elements, i.e. 0.042 ‰ fibre breakages per year; skid B: 236 breakages in 72 membrane elements, i.e. 0.076 ‰

fibre breakages per year). In the second half of May 2011, the average performance of the new membranes in skid A and B (approx. 200 L/m2

·h bar) was nearly 100 per cent higher than that of the old membranes (approx. 100 L/m2

·h bar; average of skids C, D, E, F and G).

At the beginning of 2012, after more than 5 years of operation, the skid C and D membranes were exchanged for new membranes (skid C on January 16, 2012, skid D on January 20, 2012). The permeability of the old membranes was in the range of 50-150 L/m2

·h bar. In the first weeks of operation, the new membranes showed permeability values in the range of 300 to 500 L/m2

·h bar. The old membranes from skid C and D were integrity tested and the result (Table 4) showed that after approx. 5.1 years of operation there was still a relatively low specific fibre breakage rate (skid C: 112 breakages in 72 membrane elements, i.e. 0.031 ‰ fibre breakages per year; skid D: 138 breakages in 72 membrane elements, i.e. 0.038 ‰ fibre breakages per year).

Table 4 Integrity Test Results - PREP-WRP Ultrafiltration

Integrity Results Skid Integrity

Test Date [mm/yy]

Operating Period [years]

Number of Fibre

Breakages

Fib. Breakage Rate

[‰/year]

A 06/08 1.5 3 0.003 B C D

G

06/08 06/08 06/08 12/08

1.5 1.5 1.5 2.0

0 0 0 36

0 0 0

0.025 A 11/10 3.9 119 0.042 B C D G F

04/11 01/12 01/12 03/12 04/12

4.3 5.1 5.1 5.25 5.3

236 112 138 142 135

0.076 0.031 0.038 0.038 0.035*

* Extrapolated from 40 tested elements to 72 elements

Owing to the policy of the client (IOCL) the following membrane exchange procedure has been practised. As mentioned above, the membranes of skid A and B were exchanged for spare membranes whereas the membranes of skid C and D were exchanged for new membranes. The old “intact” membrane elements (without fibre breakages) of skid A, B, C and D were reused in skid G (all 72 elements replaced in March 2012) and F (40 elements replaced in April 2012, i.e. 32 non- integrity tested, original membranes are operated in skid F; status end of May 2012). Skid E is still operated with all the 72 original membrane elements, i.e. no elements have been exchanged so far (status end of May 2012).

Basically, there are three criteria for membrane exchange: A.) Low permeability (< 100 L/m2·h bar) - necessitating a higher CEB frequency, higher energy consumption and lower plant availability. B.) TMP – should not exceed 1.5 bar in order to avoid both intensified fouling and mechanical stress. C.) Membrane integrity - number of fibre breakages should not be too high in order to avoid turbidity and an increased SDI.

Ad A) In the PRE-WRP (and also in the PNC-WRP), the permeability values have a basic tendency to fluctuate, which is due mainly to variable secondary effluent quality from upstream ETPs. Therefore, the maximum achievable permeability (average of the three highest daily 90% percentiles of the subsequent operational period - accomplished after regular or additional CEB; MaxAP) has been used as a parameter for performance evaluation. An analysis for the last two weeks of May 2012 (18 - 31 May) has shown that skid A and B (exchange for spare membranes in October 2010 and April 2011) accomplished MaxAPs of 237 and 243 L/m2·h bar respectively. Skid C and D (exchange for new membranes in January 2012) achieved MaxAPs of 390 and 210 L/m2

·h bar respectively (the reasons for the significant performance difference in skid C and D could not yet be clarified at the time of the completion of the paper). Skid G and F (old A, B, C, and D “intact” membranes reused on March 18, 2012 and April 5, 2012 respectively) attained MaxAPs of 91 and 103 L/m2·h bar. Skid E (no exchange so far) has shown a MaxAP of 90 L/m2

·h bar, i.e. as expected, reused “intact” membranes (skids G and F) and old original membranes (skid E) have comparable MaxAPs. Ad B) TMPs have been normally below 1 bar, i.e. this exchange criterion has not been exceeded. Ad C) Integrity in industrial water reclamation is not as important as in drinking water treatment. Nevertheless, the membrane elements with fibre breakages should be exchanged (or repaired) in order to maintain proper turbidity and SDI values, and subsequently to minimise the fouling potential of the RO membranes. These values were according to design (turbidity < 0.1 NTU [limit of detection] and SDI < 3) before membrane exchange (and logically also after exchange), i.e. as the fibre breakage rate was low (Table 4), no increased turbidity and SDI could be detected. One reason for reusing “intact” old membranes is to save CAPEX (for new membranes) and another is, as above mentioned, to avoid fouling of the downstream RO membranes by broken UF fibres. Whether or not a reduction in total cost (OPEX + CAPEX) will result, may be seen in the next few operational months. However, it is probable that this question might only be clarified by a detailed cost analysis study.

The following describes a result from Q2/2011 regarding the removal of the major parameters TDS, COD, and silica (monthly average values for April 2011) at the Panipat Naphtha Cracker Water Reclamation Plant. TDS in the UF permeate was reduced by reverse osmosis I from 393 mg/L (design value 800 mg/L) to 21 mg/L (94.7 % removal), whereas silica was cut by RO I from 5.6 mg/L to 1.2 mg/L (78.6 %). The COD was lowered from 26 to 16 mg/L (38.5 %) by coagulation, sedimentation and filtration, and from 16 to 14 mg/l in ultrafiltration, i.e. a reduction of 2 mg/L. This means that approximately 12.5 % of the UF inlet COD was of high molecular nature (origin: naphtha cracker and polymer unit effluents; macromolecules from polyethylene, ethylene glycol, polypropylene and polybutadien production). The design gross flux of 50 L/m2·h and a COD reduction of 2 mg/L resulted in a typical specific removal rate of 100 mg COD/m2·h, which was lower than in the PRE-WRP UF (normally > 200 mg COD/m2

·h). However, higher PNC-WRP UF COD removal rates (200 - 250 mg COD/m2

·h) were also observed within the context of sub-optimum conditions in the PNC effluent treatment plant (PNC-ETP), which probably released higher concentrations of macromolecules. As already stated, from time to time, poor treated effluent quality, caused by disruptive conditions in the biological effluent treatment plants, leads to problems in the UF process steps of both reclamation plants. Figure 6 shows the permeability of the PNC-WRP UF from December 2010 to February 2012. The massive permeability loss in January and February 2011, as well as in January 2012, was presumably caused by suboptimum conditions in the PNC-ETP. This poor performance can be mainly traced to low wastewater temperatures (and possibly inhibiting and/or partly toxic substances from the petrochemical processes). It would seem

that under these disruptive conditions more macromolecules leave the ETPs, and subsequently cause fouling on the UF membranes. Fouling was exacerbated during January/February 2011, as the sodium-hypo-chlorite dosing pumps had to be serviced, which resulted in non-optimum cleaning performance with regard to organic foulants. It is therefore advisable to employ “early warning systems” (pilot scale activated sludge plants with lower hydraulic retention times and regular activated sludge transfer from the full scale plant) upstream of the biological treatment plants, in order to detect the aforementioned inhibiting effects in advance and if necessary to divert the raw wastewater to buffer tanks. The ETPs and the reclamation plants are operated by two different water technology contractors. It would be beneficial if the entire wastewater management and reclamation system (“early warning systems”, ETPs and reclamation plants) were operated and monitored by only one experienced water technology specialist in order to avoid interface losses and subsequently ensure the optimisation of the whole system.

Figure 6 Permeability in the period of December 2010 to February 2012 - PNC-WRP

The operating costs of both reclamation plants are presented in Table 4. As can be seen in this table, the reclamation costs (OPEX) for the production of demineralised water (boiler make-up water) amount to 0.30 EUR/m3 for the PRE-WRP and 0.33 EUR/m3 for the PNC-WRP, i.e. the OPEX of the PRE-WRP is lower in spite of the higher TDS. By and large, this can be explained by the fact that the power price is higher for the PNC-WRP (0.147 EUR/kWh vs. 0.116 EUR/kWh for the PRE-WRP), the lower specific chemicals demand and the higher degree of capacity utilisation of the PRE-WRP. However, according to the higher TDS, the specific power demand of the PRE-WRP (1.4 kWh/m3) is higher than that of the PNC-WRP (1.1 kWh/ m3).

Table 4 Operating costs of PRE-WRP and PNC-WRP

Reclamation Plants Cost Type Unit PRE-WRP PNC-WRP Power [EUR/m3] 0.160 1) 0.154 2) Chemicals Manpower Maintenance, admin., etc. OPEX (Total Operating Cost)

[EUR/m3] [EUR/m3] [EUR/m3] [EUR/m3]

0.110 0.022 0.003 0.295

0.141 0.031 0.004 0.330

1) 1.41 KWh/m3, 0.114 EUR/KWh; 2) 1.07 KWh/m3, 0.144 EUR/KWh

CONCLUSIONS The realisation of the Panipat Refinery, Refinery Expansion and Naphtha Cracker projects is representative of India’s rapid industrial growth and economic development. Water management (process water production, effluent treatment, water reclamation and recycling) is a key factor in this context. At Panipat, water reclamation and recycling are essential, as no proper recipient is available and therefore the environmental authorities have requested that zero liquid discharge be implemented in the near future. Advanced technologies such as membrane filtration are of major significance, especially where the functioning of industrial (refinery and petrochemical) processes has to be guaranteed. With this in view, it is also important that the advanced multi-barrier systems employed are operated and monitored by an experienced water technology specialist. The performance of the ultrafiltration process steps (and RO) depends very much upon the performance of the upstream biological treatment processes, which in winter are disturbed by low wastewater temperatures and occasionally by the inhibiting and/or partly toxic compounds released during the refining and petrochemical processes. It is recommended that an “early warning system” (pilot scale activated sludge plant) be used upstream of the biological treatment plants in order to detect such inhibiting effects in advance. It is further recommended that the entire wastewater management and reclamation system (“early warning system”, ETPs and reclamation plants) is operated by only one experienced plant operator in order to avoid interface losses and ensure optimised performance of the whole system. Apart from environmental protection and the reliable provision of process water (mainly boiler make-up), large quantities of freshwater can be saved. This boosts the security of the industrial water supply, which could be endangered in the future due to increased demands for freshwater for agricultural and potable purposes. Last, but not least, it can be concluded that the water recycling practice described constitutes a major factor in sustainable development (environmental, social and economic) in the Panipat region. ACKNOWLEDGEMENT The authors wish to thank the Indian Oil Corporation Ltd. Panipat, and their VATECH WABAG colleagues G. Srinivasan, T. Selvakumar, B. K. Singh, B. K. Kumaran, N. Hoffmann and Ch. Walder for their support in the preparation of this paper.

REFERENCES Global Water Intelligence – Vol 13, Issue 2, February 2012, p. 28 Lahnsteiner J., Mittal R. (2010) Reuse and recycling of secondary effluents in refineries employing advanced multi-barrier systems,

Wat. Sci. Tech. 62(8), 1813–1820 VGB-R 450 L (2006) Richtlinien für die Speisewasser-, Kesselwasser- und Dampfqualität für Kraftwerke / Industriekraftwerke.

VGB Power Tech Service GmbH Essen, Germany