DOI: 10.3303/CET24114115 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Paper Received: 30 May 2024; Revised: 20 August 2024; Accepted: 6 December 2024 
Please cite this article as: Petrovič A., Rola K., Gruber S., Šantl N., Sankovič S., Čuček L., Goričanec D., Urbancl D., 2024, The Processing of 
Biological Waste from the Pharmaceutical Industry, Chemical Engineering Transactions, 114, 685-690  DOI:10.3303/CET24114115 
  

 CHEMICAL ENGINEERING TRANSACTIONS  
 

VOL. 114, 2024 

A publication of 

 

The Italian Association 
of Chemical Engineering 
Online at www.cetjournal.it 

Guest Editors: Petar S. Varbanov, Min Zeng, Yee Van Fan, Xuechao Wang 

Copyright © 2024, AIDIC Servizi S.r.l. 

ISBN 979-12-81206-12-0; ISSN 2283-9216 

The Processing of Biological Waste from the Pharmaceutical 

Industry 

Aleksandra Petrovič*, Klemen Rola, Sven Gruber, Neža Šantl, Saša Sankovič, Lidija 

Čuček, Darko Goričanec, Danijela Urbancl 

Faculty of Chemistry and Chemical Engineering, University of Maribor, Maribor, Slovenia 

aleksandra.petrovic@um.si 

The pharmaceutical industry produces waste that can pose significant environmental and health risks if not 

handled properly. The aim of this research is to investigate the microfiltration (MF) method for the treatment of 

pharmaceutical waste mycelia (fermentation residue) and to test different operating conditions (different 

permeate flows, operating pressures, and treatment times) to identify and determine the optimum setting 

conditions. The products resulting from the best operating conditions permeate and retentate and were then 

subjected to further chemical characterisation. 

The results showed that the operation of the MF pilot plant, consisting of 4 sequentially coupled 0.1 µm ceramic 

ZrO2 membranes with a total membrane area of 56 m2, was optimal at a permeate flow of 1.2 m3/h (pressure of 

2 bar, temperature of 60 °C) with a permeate flux of 21.4 L/(m2×h). Two different operating times (3.5 and 8 h) 

were tested under these conditions without any clogging of the membranes being detected, neither in the long 

nor in the short time of operation. The chemical analysis showed that MF is highly efficient in removing chemical 

oxygen demand (COD), which decreased by 67 %, although the removal of other small micropollutants was less 

efficient. 

1. Introduction 

The waste generated by the pharmaceutical industry can pose a serious threat to the environment and human 

health if it is not properly treated and disposed of (Adeoye et al., 2024). Pharmaceutical waste comes mainly 

from pharmaceutical production, which can be divided into the production of active pharmaceutical ingredients 

(APIs) and the production of final pharmaceutical products (FPP). The main problem with waste streams from 

the pharmaceutical industry is the transfer of antibiotic resistance genes into the food chain, which can lead to 

bacteria becoming immune to antibiotics, which is why appropriate treatment is required (Kotwani et al., 2021). 

Besides, another threat to human health and freshwater reserves is the rising of emerging contaminants in the 

water and environment, such as pharmaceutical drugs (Alfonso-Muniozguren et al., 2021).  

One of the ways of producing pharmaceutical ingredients is through fermentation, which also generates huge 

amounts of biological waste consisting of the fermentation medium, metabolites, amino acids and other 

components, including cell residues, nutrients, minerals and traces of APIs (Jaseem et al., 2017). It is estimated 

that the production of 1 t of API produces between 8 and 10 t of fermentation waste (Hui et al., 2023). 

The method chosen for the processing and disposal of pharmaceutical waste depends primarily on its 

composition. However, from a circular economy and sustainability perspective, the waste streams could be used 

to recover nutrients or to produce other value-added products. In general, fermentation waste (mycelium) is 

classified as non-hazardous and is suitable for various biological treatment methods, such as aerobic or 

anaerobic degradation with bacteria or biological treatment with fungi (Gong et al., 2020). As it contains large 

amounts of water (less than 8 % dry matter), its treatment and disposal are associated with high costs. In 

addition to fermentation residues, other waste streams are also produced in the pharmaceutical industry, 

including wastewater, which can contain various organic pollutants, suspended and dissolved solids, chlorides, 

sulfides, oils and heavy metals (Kumar et al., 2024). Their presence in the environment causes concern, as they 

are not biodegradable, are often carcinogenic, and can easily accumulate and cause damage to organs in the 

685



human body (Okeke et al., 2022). Various studies were dedicated to treatment of pharmaceutical waste, with 

the most investigated processes being biological like anaerobic digestion (Yang et al., 2024), physico-chemical 

treatment like membrane filtration (Kumar et al., 2024), photocatalytic degradation (Bhattacharjee and 

Ahmaruzzaman, 2024), and thermal treatment, such as pyrolysis (Mgharbel et al., 2023) and hydrothermal 

carbonisation (Javid et al., 2021). Despite many studies, several questions regarding the treatment of such 

waste remain unsolved, and their complex composition requires the treatment of each waste separately.  

The aim of this study was to investigate the MF of waste mycelium (fermentation residue) from the 

pharmaceutical industry and to find the optimal way of processing it, depending on its physico-chemical 

properties. Different operating conditions were tested, and the products, permeate and retentate, obtained from 

the experiment with the most optimal operating conditions were characterised using different chemical methods. 

They were subjected to analyses such as COD, total phosphorus (TP), total nitrogen (TN) and others. Based 

on the results of the analyses, the optimal operating conditions for the treatment of a real sample of waste 

mycelium were proposed. The study's distinctive contribution lies in its comprehensive approach to address the 

treatment of specific pharmaceutical waste mycelium sample. This is achieved through the utilisation of a pilot-

scale MF unit and the optimisation of specific operational parameters. 

2. Materials and methods 

2.1 Feedstock 

The waste mycelium resulting from the production of an API for one of the commonly used antibiotics was 

collected in one of the Slovenian pharmaceutical companies and treated by membrane filtration. The waste 

mycelium was not pretreated with any other method prior to membrane filtration.  

2.2 Treatment of mycelium 

The raw mycelium was treated by pilot MF equipment, which consists of a mycelium-fed buffer vessel equipped 

with a mixer. A pump is installed under the vessel, which pumps the fluid (mycelium) to the MF unit. The unit 

consists of 4 sequential stages, with 0.1 µm ceramic ZrO2 membranes with a net area of 56 m2, set in a Cr-Ni-

Mo steel casing. Each stage is composed of multiple parallel modules. In the first three stages, three parallel 

modules are installed at each stage and in the last stage, two parallel modules are installed. Modules in each 

stage are of the same capacity, where the first stage has the highest, and the last stage has the lowest capacity. 

The second and third stages have the same intermediate capacity. Before each stage, pumps raise the pressure 

to the appropriate value and simultaneously produce the heat, raising the feedstock temperature. To counteract 

this, a tube heat exchanger is installed at each stage, providing water cooling. Two tubular heat exchangers are 

installed at the outlet of retentate and permeate, which are collected as products of membrane filtration to cool 

each outlet. For MF, filtration pressure, temperature (average across stages) and permeate flowrate at each MF 

stage, i.e. MF unit, can be set. The volume flowrates of permeate and feed are measured with magnetic-

inductive flowmeters. Diaphragm pressure sensors are used to measure the pressure, and temperature is 

measured using temperature sensors with Pt100 transducers. The data is measured on-line at each stage and 

sent to the equipment display, where it is updated regularly. 

During the experiment, temperatures, inlet and outlet membrane pressures of the retentate side, and flowrates 

of permeate were recorded by taking a snapshot of the display every 0,5 h during operation. The MF was 

performed under the next set of conditions: feed mycelium flowrate of 3.0 m3/h, temperature of 60 °C and 

pressure of 2 bar. The operating time varies depending on the experiment. Three different permeate flowrates 

were tested: 1.0, 1.2 and 1.7 m3/h. More specifically, for the experiment at flowrate, 1.2 m3/h, the flowrates of 

permeate were set to 0.5, 0.3, 0.3, and 0.1 m3/h at stages 1, 2, 3, and 4, considering the capacity difference 

between the stages. The flowrates were lower in each subsequent stage, with stages 2 and 3 allowing the same 

permeate flow rates. The experiments at the highest permeate flow rate (1.7 m3/h) were conducted at two 

different pressures (2 and 2.5 bar), while at a permeate flow rate of 1.2 m3/h the two different operating times 

were tested (3.5 and 8 h). When MF was operated for 8 h, a semi-stationary state was achieved around 1 h of 

filtration. The permeate and retentate samples collected in the experiment with the optimal operating conditions 

were further chemically characterised. The samples were taken from the last stage of MF after 8 h of operation 

before the columns were switched to the washing sequence.  

2.3 Measurement of chemical parameters 

The mycelium raw waste stream, permeate and retentate were collected immediately after MF tests and then 

stored at 4 °C in the fridge until further chemical analyses. The samples were analysed for COD, TN, ammonia 

nitrogen (N-NH4
+), TP and phosphate (PO4

3-) using appropriate standard methods. In addition, the pH value 

was measured using the pH sensor of the Pasco producer. 

686



3. Results and discussion 

3.1 The results of microfiltration tests 

The results of MF experiments are shown in Figure 1. At the highest permeate flowrate and the highest pressure 

tested (1.7 m3/h, 62.5 °C, 2 h, 2.5 bar), the MF was stopped after ~1.5 h of operation because the pressures at 

the membrane outlets increased above 3.5 bar, even though the pressure was set to 2.5 bar. This is inferred to 

be due to a very dense i.e., viscous concentrate. Despite the increase in pressure, the concentrate and permeate 

flows remained constant, and there were no noticeable changes in the opening of the permeate valves. The 

permeate flux, calculated by the equation proposed by Pan et al. (2015), was 30.4 L/(m2×h). 

In the second experiment that was conducted at the same permeate flow and temperature (1.7 m3/h, 62.5 °C) 

but lower operating pressure (2 bar), the impact of operating pressure on the MF process was studied. Despite 

the lower operating pressure, the pressure for the individual membrane filtration columns still increased with 

operating time duration, although the increase was slightly lower. The outlet pressure of all membranes was 

similar, while the inlet pressure significantly differed. The highest pressure was observed in the case of the first 

membrane stage and the lowest at the third stage. The other two stages (2 and 4) were within the pressures of 

stages 1 and 3 and exhibited more equal pressures to each other. However, after 2 h of the operation, the 

experiment was stopped as an increase in pressure was observed. This indicated that the permeate flow was 

too high. Therefore, in the next experiment, the permeate flow of 1.0 m3/h was tested. 

The experiment at a permeate flow of 1.0 m3/h (60° C, 2 bar) runs 3.5 h, wherein the calculated permeate flux 

was 17.9 L/(m2×h). During the operation, except at the beginning of the experiment, no significant pressure 

increase was observed in any of the membrane stages, and no clogging was detected. Regarding the operating 

temperature, the measurements revealed the highest temperature in the last stage (stage 4), followed by stages 

3, 2 and 1. This indicated that during the MF, the temperature of the feedstock increased due to several reasons. 

The fluctuation of the temperature at each MF stage can be attributed to the nature of regulation. Each pump, 

besides raising the pressure, also introduces heat into each stage feed, raising its temperature. During MF, it is 

likely that the temperature also increases due to the friction. As mentioned in section 2.2, the cooling for each 

stage is provided as a result. It is thought that in the first and second stages, the temperature cannot reach 60 

°C since not enough heat is introduced to the feed. This then allows the temperature of the third and last stages 

to reach higher values to balance lower stage 1 and 2 temperatures. As a result, it is thought that the first two 

stages do not cool much. This can also be noticed in all the diagrams, where the first two stages have 

significantly more uniform curves compared to the last two stages. Significant fluctuations could be attributed 

mostly to the regulation’s natural slow response of temperature-regulated systems and to the allowed set 

temperature interval of ±2 °C, allowing the fluctuation between 58 °C and 62 °C.  

Due to the encouraging results obtained at a permeate flow of 1.0 m3/h, in the next experiment, the permeate 

flow was increased to 1.2 m3/h. Similar results were obtained in the case of lower permeate flow. In addition, 

the temperature and the pressure were relatively constant, and no significant changes were noticed during 3.5 h 

of operating. In all four stages, a temperature rise was observed at the start of operation due to start-up to reach 

the temperature setpoint. The permeate flux in this experiment was higher because of the higher permeate flow 

and was equal to 21.4 L/(m2×h). 

To investigate the impact of operating time on the MF, the previously mentioned experiment at permeate flow 

of 1.2 m3/h was repeated at the longer operating time (8 h). The temperatures varied between 50 and 73 °C, 

depending on the MF stage, with an average value of 60 °C for all four stages together. Modules 3 and 4 

exhibited higher temperature increases than the other two stages, where the temperature was more constant. 

A slight increase in the pressure was also observed in the stages, first after 1.5 h of operation and the second 

near 4.5 h of operation, which was again followed by a slight decrease. The changes in pressure are most likely 

also related to the temperature. It is thought that the drop in temperature causes the viscosity to rise and density 

to increase, making it harder to achieve the specified permeate flowrate, causing the pressure to increase. This 

can be clearly seen when looking at the segment between 1 h and 4 h of operating time. In the next time section, 

however, an increase in pressure is noticed at the same time as the temperature is increased, which undermines 

the dependence on operating pressures. It is also possible that some time lag is present since the change in 

pressure won’t take effect immediately after the temperature change. To prove this, the MF would need to be 

operated multiple times at longer periods of time. Nevertheless, the valves that regulate the flowrate of permeate 

were opened to the same extent during the whole time of operation, and clearly, no drop in permeate flowrate 

was observed because of this. However, as the operation was stable most of the time, the permeate flow of 

1.2 m3/h was adopted as the most optimal among the tested flows.  

The literature review revealed that membrane filtration processes are also considered highly efficient for the 

treatment of pharmaceutical waste streams in other studies. For example, hybrid membrane filtration and 

687



advanced oxidation processes were found to be highly effective in the treatment of pharmaceutical wastewater 

(Rosman et al., 2018). Nanofiltration alone and its combination with electrodialysis with bipolar membranes was 

also successfully used to recover nutrients from a microbial fermentation effluent (Knežević et al., 2022), and a 

biological system coupled with membranes, e.g. a membrane bioreactor, was efficient in the removal of 

pharmaceuticals from water (Alfonso-Muniozguren et al., 2021). 

 

 

 

 

 

Figure 1: The temperatures, pressures and permeate flow rates in the MF columns during the experiments 

performed at permeate flow of: 1.7 m3/h and 2.5 bar (a, b, c), 1.7 m3/h and 2 bar (d, e, f), 1.0 m3/h and 2 bar (g, 

h, i), 1.2 m3/h at shorter operating time (j, k, l) and 1.2 m3/h at longer operating time (m, n, o) 

688



3.2 Chemical characteristics of mycelium and products of microfiltration 

The chemical properties of raw mycelium, the retentate and the permeate obtained by MF at 1.2 m3/h are shown 

in Figure 2. Raw mycelium contains 81.7 g/L COD, 4,460 mg/L TN and 640 mg/L TP.  The content of all 

parameters, including TN, ammonium nitrogen, TP and phosphate in the permeate decreased compared to the 

raw mycelium. The removal efficiency of TP was higher (57 %) than that of TN (24 %). Microfiltration and 

ultrafiltration membranes are primarily used to remove relatively large particulate matter, macromolecules and 

sub-molecular organic groups, proteins and some higher ions, while smaller organic and inorganic 

micropollutants and ions can only be removed by nanofiltration or reverse osmosis (Gupta et al., 2022). The pH 

of the raw mycelium was acidic (around 5.2), as was that of the permeate (6.1). 

The COD, which reflects the oxygen consumption due to the chemical oxidation of organic substances, 

decreased by 67 % in the permeate and increased by 19.5 % in the retentate. Compared to the results of this 

study, nanofiltration of spent fermentation broth in one of the previous studies removed between 78 and 85 % 

of dissolved organic carbon (DOC), while the combination of nanofiltration with electrodialysis with bipolar 

membranes was an even more promising treatment, as it removed 95–98 % DOC, but on the other hand 

consumed more energy (Knežević et al., 2022). Reverse osmosis filtration of oxytetracycline wastewater 

reduces the COD content from 10,000 mg/L to less than 200 mg/L, and the additional treatment by ultrafiltration 

recovers more than 60 % of the oxytetracycline (Li et al., 2004). 

 

Figure 2: The content of a) COD, b) TN and N-NH4
+, and c) TP and PO4

3- in raw mycelium, retentate and 

permeate 

4. Conclusions 

The MF of mycelium from the pharmaceutical industry was investigated with a pilot MF unit under different 

operating conditions (permeate flow, operating time and pressure) and the optimum operating conditions for the 

treatment of the mycelium waste sample were determined. The problem with mycelium is its high viscosity, 

which leads to clogging of the membranes and an increase in operating pressure, so the optimal conditions 

should be determined individually for each type of mycelium. The chemical analyses showed that MF with the 

pilot MF unit tested was very efficient in reducing the COD in the permeate and less efficient in removing nitrogen 

and phosphorus. However, the MF system reduces the amount of mycelium that needs to be further treated 

with other methods, which can translate into lower treatment costs and is in line with the sustainable approach 

and environmental protection. The main outcome is the determination of optimal operating parameters for the 

given membranes and the specific mycelium sample. The permeate obtained could be further treated in a 

biological wastewater treatment plant. Further studies could aim to investigate the combination of ultrafiltration 

with other advanced treatment processes, such as reverse osmosis, to increase treatment efficiency and 

recover nutrients from the waste mycelium, such as nitrogen or phosphorus. 

References 

Adeoye J.B., Tan Y.H., Lau S.Y., Tan Y.Y., Chiong T., Mubarak N.M., Khalid M., 2024, Advanced oxidation and 

biological integrated processes for pharmaceutical wastewater treatment: A review. J Environ Manage, 353, 

120170. 

Alfonso-Muniozguren P., Serna-Galvis E.A., Bussemaker M., Torres-Palma R.A., Lee J., 2021, A review on 

pharmaceuticals removal from waters by single and combined biological, membrane filtration and ultrasound 

systems. Ultrasonics Sonochemistry, 76, 105656. 

Bhattacharjee B., Ahmaruzzaman M., 2024, Photocatalytic degradation of pharmaceuticals: Insights into 

biochar modification and degradation mechanism. Next Materials, 5, 100238. 

0

1,500

3,000

4,500

Raw
mycelium

Retentate Permeate

T
N

, 
N

-N
H

4
+

(m
g

O
2
/
L
)

TN N-NH₄+b)

0

20,000

40,000

60,000

80,000

100,000

120,000

Raw
mycelium

Retentate Permeate

C
O

D
 (

m
g

O
2
/
L
)

a)

0

200

400

600

800

1,000

Raw
mycelium

Retentate Permeate
T

P
, 

P
O

4
3

-
(m

g
/
L
)

TP PO₄³¯c)

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Gong P., Liu H., Xin Y., Wang G., Dai X., Yao J., 2020, Composting of oxytetracycline fermentation residue in 

combination with hydrothermal pretreatment for reducing antibiotic resistance genes enrichment. 

Bioresource Technology, 318, 124271. 

Gupta S., Singh A., Sharma T., Kaur R., Khandelwal V., Rawat K.D., Pathak S., Sharma M.K., Singh J., Shah 

M.P., Chauhan S.C., Parashar D., Shankar P., Kashyap V.K., 2022, Chapter 2 - Applications of ultrafiltration, 

nanofiltration, and reverse osmosis in pharmaceutical wastewater treatment. In: Shah M.P., Rodriguez-

Couto S. (Eds.), Development in Wastewater Treatment Research and Processes, Elsevier, Oxford, United 

Kingdom, 33-49. 

Hui X., Fang W., Wang G., Liu H., Dai X., 2023, Waste recycling of antibiotic mycelial residue: The feasible 

harmless treatment and source control of antibiotic resistance. Journal of Cleaner Production, 401, 136786. 

Jaseem M., Kumar P., John R., 2017, An overview of waste management in pharmaceutical industry. The 

Pharma Innovation Journal, 6, 158-161. 

Javid F., Ang T.N., Hanning S., Svirskis D., Burrell R., Taylor M., Wright L.J., Baroutian S., 2021, Hydrothermal 

deconstruction of local anesthetics (bupivacaine and lignocaine) in pharmaceutical waste. Journal of 

Environmental Chemical Engineering, 9(5), 106273. 

Knežević K., Rastädter K., Quehenberger J., Spadiut O., Krampe J., Kreuzinger N., 2022, Circular production – 

Evaluation of membrane technologies for nutrient recycling from a microbial fermentation effluent. Journal 

of Cleaner Production, 377, 134436. 

Kotwani A., Joshi J., Kaloni D., 2021, Pharmaceutical effluent: a critical link in the interconnected ecosystem 

promoting antimicrobial resistance. Environmental Science and Pollution Research, 28(25), 32111-32124. 

Kumar R., Awino E., Njeri D.W., Basu A., Chattaraj S., Nayak J., Roy S., Khan G.A., Jeon B.H., Ghosh A.K., 

Pal S., Banerjee S., Rout P., Chakrabortty S., Tripathy S.K., 2024, Advancing pharmaceutical wastewater 

treatment: A comprehensive review on application of catalytic membrane reactor-based hybrid approaches. 

Journal of Water Process Engineering, 58, 104838. 

Li S.-Z., Li X.-Y., Wang D.-Z., 2004, Membrane (RO-UF) filtration for antibiotic wastewater treatment and 

recovery of antibiotics. Separation and Purification Technology, 34(1), 109-114. 

Mgharbel M., Halawy L., Milane A., Zeaiter J., Saad W., 2023, Pyrolysis of pharmaceuticals as a novel means 

of disposal and material recovery from waste for a circular economy. Journal of Analytical and Applied 

Pyrolysis, 172, 106014. 

Okeke E.S., Ezeorba T.P.C., Okoye C.O., Chen Y., Mao G., Feng W., Wu X., 2022, Environmental and health 

impact of unrecovered API from pharmaceutical manufacturing wastes: A review of contemporary treatment, 

recycling and management strategies. Sustainable Chemistry and Pharmacy, 30, 100865. 

Pan S.F., Zhu M.P., Chen J.P., Yuan Z.H., Zhong L.B., Zheng Y.M., 2015, Separation of tetracycline from 

wastewater using forward osmosis process with thin film composite membrane – Implications for antibiotics 

recovery. Separation and Purification Technology, 153, 76-83. 

Rosman N., Salleh W.N.W., Mohamed M.A., Jaafar J., Ismail A.F., Harun Z., 2018, Hybrid membrane filtration-

advanced oxidation processes for removal of pharmaceutical residue. Journal of Colloid and Interface 

Science, 532, 236-260. 

Yang G., Xu Y., Wang J., 2024, Antibiotic fermentation residue for biohydrogen production: Inhibitory 

mechanisms of the inherent antibiotic. Science of the Total Environment, 944, 173986. 

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